--- title: "Cancel Scheduled Email" method: DELETE path: "/emails/scheduled/{transmissionId}" tags: ["Emails"] --- # Cancel Scheduled Email `DELETE /emails/scheduled/{transmissionId}` ## Request - Base URL: `https://app.lettr.com/api` - URL: `https://app.lettr.com/api/emails/scheduled/{transmissionId}` - Auth: HTTP bearer Cancel a scheduled email before it is injected into SparkPost, and return the cancelled email. **Breaking change.** Cancellation used to be delegated to SparkPost's per-transmission DELETE endpoint, which SparkPost retired — the call failed every time. Lettr now owns the schedule, so a cancellation either genuinely stops the send or says truthfully that it could not. Only an email in state `scheduled` can be cancelled. Once the dispatcher has claimed it (`sending`), or it has already been injected (`sent`) or cancelled (`cancelled`), the request fails with `409 schedule_cancellation_failed` — SparkPost offers no per-message recall after injection. A sandbox key can only cancel the emails it scheduled itself. ## Path parameters - `transmissionId` string, required ## Response `200` Scheduled transmission cancelled successfully. The email was never handed to SparkPost. - object - `message` string, required - `data` ScheduledEmailResponse, required: A scheduled email held by Lettr. This is the `data` object of `POST /emails/scheduled`, `GET /emails/scheduled/{transmissionId}` and `DELETE /emails/scheduled/{transmissionId}`, and each entry of `scheduled_emails` in `GET /emails/scheduled`. **Breaking change.** Scheduled emails are no longer parked inside SparkPost with `options.start_time` — SparkPost retired its per-transmission GET and DELETE endpoints. Lettr now holds the email in its own store and injects it into SparkPost when it is due, so `request_id` is Lettr's own `sch_...` id, `transmission_id` is a separate field that stays `null` until injection, and `state` values are Lettr's own rather than SparkPost's pass-through states. - `request_id` string, required: Lettr's identifier for the scheduled email, prefixed `sch_`. Pass this value to `GET` and `DELETE /emails/scheduled/{transmissionId}`. Before this change the field held SparkPost's transmission id. - `transmission_id` string, nullable, required: SparkPost's transmission id. `null` until the email is injected into SparkPost at its delivery time. This is the value that appears as `transmission_id` on your webhook events, so correlate webhooks on this field — not on `request_id`. - `state` 'scheduled' | 'sending' | 'sent' | 'cancelled' | 'failed', required: Current state of the scheduled email. `scheduled` — waiting for its delivery time, the only state that can be cancelled. `sending` — claimed by the dispatcher and being injected right now. `sent` — injected into SparkPost; delivery detail then comes from `events`. `cancelled` — cancelled before injection, never handed to SparkPost. `failed` — injection was attempted and gave up, see `failure_reason`. - `scheduled_at` string, date-time, required: The delivery time in ISO 8601 format (UTC). - `from` string, email, required: Sender email address. - `from_name` string, nullable, required: Sender display name. - `subject` string, nullable, required: Email subject line. - `recipients` string[], required: List of recipient email addresses. - `num_recipients` integer, required: Total number of recipients. - `accepted` integer, required: Number of recipients accepted for delivery. Before injection this is what Lettr accepted; afterwards it is SparkPost's own count. - `rejected` integer, required: Number of recipients rejected. `0` before injection. - `tag` string, nullable, required: Tag supplied when the email was scheduled, used for tracking and analytics. - `failure_reason` string, nullable, required: Why injection gave up. Only set when `state` is `failed`. - `events` EmailEvent[], required: Delivery events for this email. Empty until the email has been sent; populated with injection, delivery, bounce, open, click and other events once it has been injected into SparkPost. - union: An email event. The `type` field determines which additional fields are present. All event types share common fields defined in `CommonEventProperties`. - InjectionEvent: Fired when a message is received by the system and queued for delivery. - `event_id` string, required: Unique identifier for the event - `type` 'injection', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `initial_pixel` boolean, nullable: Whether initial open tracking pixel was included - DeliveryEvent: Fired when a message is successfully delivered to the recipient's mail server. - `event_id` string, required: Unique identifier for the event - `type` 'delivery', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `queue_time` integer, nullable: Time spent in queue in milliseconds - `outbound_tls` string, nullable: Whether TLS was used for outbound delivery ("1" = yes) - BounceEvent: Fired when a message is permanently rejected by the recipient's mail server. - `event_id` string, required: Unique identifier for the event - `type` 'bounce', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `bounce_class` integer, nullable: Bounce classification code (e.g. 10 = Invalid Recipient, 30 = Generic Bounce) - `error_code` string, nullable: SMTP error code - `reason` string, nullable: Human-readable bounce reason - `raw_reason` string, nullable: Raw SMTP reason string - `num_retries` integer, nullable: Number of delivery retries attempted - `device_token` string, nullable: Device token if applicable - DelayEvent: Fired when a message delivery is temporarily delayed (will be retried). - `event_id` string, required: Unique identifier for the event - `type` 'delay', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `reason` string, nullable: Human-readable delay reason - `raw_reason` string, nullable: Raw SMTP reason string - `error_code` string, nullable: SMTP error code - `bounce_class` integer, nullable: Bounce classification code - `num_retries` integer, nullable: Number of delivery retries attempted so far - `queue_time` integer, nullable: Time spent in queue in milliseconds - `outbound_tls` string, nullable: Whether TLS was used for outbound delivery - OutOfBandEvent: Fired when a remote mail server sends an asynchronous bounce after initially accepting the message. - `event_id` string, required: Unique identifier for the event - `type` 'out_of_band', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `bounce_class` integer, nullable: Bounce classification code - `error_code` string, nullable: SMTP error code - `reason` string, nullable: Human-readable bounce reason - `raw_reason` string, nullable: Raw SMTP reason string - `device_token` string, nullable: Device token if applicable - SpamComplaintEvent: Fired when a recipient marks the message as spam via a feedback loop. - `event_id` string, required: Unique identifier for the event - `type` 'spam_complaint', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `fbtype` string, nullable: Feedback type (e.g. "abuse") - `report_by` string, nullable: Who reported the spam - `report_to` string, nullable: Where the spam report was sent - PolicyRejectionEvent: Fired when a message is rejected due to policy (e.g. suppression list, rate limiting). - `event_id` string, required: Unique identifier for the event - `type` 'policy_rejection', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `remote_addr` string, nullable: Remote IP address - `reason` string, nullable: Human-readable rejection reason - `raw_reason` string, nullable: Raw rejection reason - `error_code` string, nullable: Error code - `bounce_class` integer, nullable: Bounce classification code - ClickEvent: Fired when a recipient clicks a tracked link in the email. - `event_id` string, required: Unique identifier for the event - `type` 'click', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `target_link_url` string, nullable: The URL that was clicked - `target_link_name` string, nullable: The name/label of the clicked link - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the click - OpenEvent: Fired when a recipient opens the email (subsequent opens after the initial open). - `event_id` string, required: Unique identifier for the event - `type` 'open', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the open - `initial_pixel` boolean, nullable: Whether this was triggered by the initial tracking pixel - InitialOpenEvent: Fired the first time a recipient opens the email. - `event_id` string, required: Unique identifier for the event - `type` 'initial_open', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the open - `initial_pixel` boolean, nullable: Whether this was triggered by the initial tracking pixel - AmpClickEvent: Fired when a recipient clicks a tracked link in an AMP email. - `event_id` string, required: Unique identifier for the event - `type` 'amp_click', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `target_link_url` string, nullable: The URL that was clicked - `target_link_name` string, nullable: The name/label of the clicked link - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the click - AmpOpenEvent: Fired when a recipient opens an AMP email (subsequent opens). - `event_id` string, required: Unique identifier for the event - `type` 'amp_open', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the open - `initial_pixel` boolean, nullable: Whether this was triggered by the initial tracking pixel - AmpInitialOpenEvent: Fired the first time a recipient opens an AMP email. - `event_id` string, required: Unique identifier for the event - `type` 'amp_initial_open', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `user_agent` string, nullable: Raw user agent string - `user_agent_parsed` UserAgentParsed: Parsed user agent information from the open/click event. - `agent_family` string, nullable: Browser or email client family - `device_brand` string, nullable: Device brand (e.g. Apple, Samsung) - `device_family` string, nullable: Device family (e.g. iPhone, Desktop) - `os_family` string, nullable: Operating system family - `os_version` string, nullable: Operating system version - `is_mobile` boolean, nullable: Whether the device is mobile - `is_proxy` boolean, nullable: Whether the request came through a proxy - `is_prefetched` boolean, nullable: Whether the open was prefetched by an email provider (e.g. Gmail Image Proxy, Apple Mail Privacy Protection). If true, this may not represent a real human open. - `geo_ip` GeoIp: Geolocation data derived from the IP address of the open/click event. - `country` string, nullable: ISO 3166-1 alpha-2 country code - `region` string, nullable: Region or state code - `city` string, nullable: City name - `latitude` number, nullable: Latitude - `longitude` number, nullable: Longitude - `zip` string, nullable: ZIP code - `postal_code` string, nullable: Postal code - `ip_address` string, nullable: IP address of the open - `initial_pixel` boolean, nullable: Whether this was triggered by the initial tracking pixel - GenerationFailureEvent: Fired when the system fails to generate a message (e.g. template rendering error). - `event_id` string, required: Unique identifier for the event - `type` 'generation_failure', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `reason` string, nullable: Human-readable failure reason - `raw_reason` string, nullable: Raw failure reason - `error_code` string, nullable: Error code - GenerationRejectionEvent: Fired when the system rejects message generation (e.g. policy violation). - `event_id` string, required: Unique identifier for the event - `type` 'generation_rejection', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - `reason` string, nullable: Human-readable rejection reason - `raw_reason` string, nullable: Raw rejection reason - `error_code` string, nullable: Error code - ListUnsubscribeEvent: Fired when a recipient uses the List-Unsubscribe header to unsubscribe. - `event_id` string, required: Unique identifier for the event - `type` 'list_unsubscribe', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version - LinkUnsubscribeEvent: Fired when a recipient clicks an unsubscribe link in the email body. - `event_id` string, required: Unique identifier for the event - `type` 'link_unsubscribe', required: The event type - `timestamp` string, required: When the event occurred (ISO 8601) - `request_id` string, required: The transmission/request ID that generated this event - `rcpt_to` string, email, required: Recipient email address - `raw_rcpt_to` string, email, required: Original recipient email address before any modifications - `recipient_domain` string, required: Domain of the recipient - `mailbox_provider` string, required: Mailbox provider of the recipient - `mailbox_provider_region` string, required: Region of the mailbox provider - `message_id` string, nullable: SMTP message ID - `subject` string, nullable: Email subject line - `friendly_from` string, nullable: Friendly from address - `sending_domain` string, nullable: The sending domain - `sending_ip` string, nullable: IP address used to send the email - `click_tracking` boolean, nullable: Whether click tracking was enabled - `open_tracking` boolean, nullable: Whether open tracking was enabled - `transactional` boolean, nullable: Whether this was a transactional message - `msg_size` integer, nullable: Message size in bytes - `injection_time` string, nullable: When the message was injected into the system (ISO 8601) - `rcpt_meta` unknown - `campaign_id` string, nullable: Campaign identifier - `template_id` string, nullable: Template identifier - `template_version` string, nullable: Template version - `ip_pool` string, nullable: IP pool used for sending - `msg_from` string, nullable: Envelope sender (MAIL FROM) - `rcpt_type` string, nullable: Recipient type - `rcpt_tags` string[], nullable: Recipient tags - `amp_enabled` boolean, nullable: Whether AMP was enabled - `delv_method` string, nullable: Delivery method (e.g. esmtp) - `recv_method` string, nullable: Reception method (e.g. rest) - `routing_domain` string, nullable: Routing domain - `scheduled_time` string, nullable: Scheduled delivery time if the email was scheduled - `ab_test_id` string, nullable: A/B test identifier - `ab_test_version` string, nullable: A/B test version ## Other responses - `401`: Unauthorized - Missing or invalid API key - `403`: Forbidden - API key does not have the required scope - `404`: Scheduled transmission not found. The id is unknown, or it belongs to another team or another sandbox key. - `409`: The email can no longer be cancelled: it has already been sent, was already cancelled, or is being injected right now. - `500`: Internal server error - `503`: Service unavailable - the API key could not be verified, so the request was not processed. This does not mean the key is invalid; retry after the delay given in the Retry-After header. --- [API](https://skmtc.dev/lettr/apis/lettr-api.md) · [All operations](https://skmtc.dev/lettr/apis/lettr-api/llms.txt) · [OpenAPI document](https://skmtc.dev/lettr/apis/lettr-api/revisions/48ef0dac1ebd?raw)