Sign in
Email Messages

Create or send an email message

Queues, schedules, or sandbox-sends an email message. The legacy /v2/emails POST route is a backward-compatible alias for this operation.

subject is required unless template_id is supplied. When using template_id, do not also provide subject, html_body, or text_body; the template is rendered with template_variables.

Note: template lookup failures (not found, wrong account) return 400, not 404.

post/email_messages

Headers

Idempotency-Keystring

Optional opaque, unquoted key for safely retrying the same logical request. Keys must contain 1 to 255 letters, numbers, hyphens, or underscores. Generate a unique UUID v4 for each operation and reuse it only when retrying that operation with the same request. Invalid headers—including duplicate, empty, malformed, or overlong values—return 400 with error code 10015. A request already in progress with the same key returns 409; reusing the key with a different request returns 422. Only successful responses are replayed, for up to 24 hours. Do not include sensitive data in the key.

Request body

forward_of_message_idstring uuid nullable

Telnyx message UUID of the message this send forwards. Forwarded messages start a NEW thread per RFC 5322 — NO In-Reply-To or References headers are set on the outbound MIME. The id is recorded in the message's metadata for EDR provenance only.

The id is validated as a UUID but is NOT looked up against the message store — existence is the caller's responsibility (the forward is pure metadata; it does not affect delivery). Cannot be combined with in_reply_to_message_id (422).

from_namestring

Optional display name for string from; overrides from.name when provided.

group_idstring uuid nullable

Optional unsubscribe-group UUID used for group-scoped suppression checks and unsubscribe handling.

headersobject

Custom email headers. Write-only; not returned in responses.

html_bodystring

HTML email body. Returned only by GET /email_messages/{id}; omitted from create and list responses.

ignore_suppressionboolean

When true, allows delivery to recipients whose suppressions explicitly permit an override. Hard bounces, spam complaints, and invalid-address suppressions cannot be overridden. Requires the email:override API scope.

in_reply_to_message_idstring uuid nullable

Telnyx message UUID of the message this send replies to. When provided, the API sets RFC 5322 In-Reply-To and References headers on the outbound MIME so the recipient's mailbox (Gmail/Outlook) threads it correctly. The parent is looked up under the caller's account scope; a UUID belonging to another account yields a non-enumerating 404.

Wire-only (Phase 1): the API sets the headers and does NOT resolve or mutate thread_id on the server side. Messages sent without this parameter are standalone (no threading headers injected).

Cannot be combined with forward_of_message_id (422).

inline_cssboolean
metadataobject

Custom metadata. Write-only; not returned in responses.

reply_to_allboolean nullable

Indicates a reply-all intent. In Phase 1 (wire-only) this does not change the threading headers — recipient selection is customer- controlled (to/cc), and a thread is not defined by its audience. When the referenced message has no thread context, reply-all degrades to a plain reply (parent ID only in References). The resolution engine (separate work) will expand the ancestor chain at a later phase with no API change.

Only meaningful alongside in_reply_to_message_id.

sandbox_modeboolean
scheduled_atstring date-time nullable

Future ISO 8601 time to schedule sending. Invalid or past timestamps are silently ignored and the email is sent immediately. The legacy alias send_at is still accepted for backward compatibility; when both are provided, scheduled_at wins.

send_atstring date-time

Deprecated alias for scheduled_at.

subjectstring

Required unless template_id is supplied. When using a template, the template's subject is rendered; if the template has no subject or renders empty, the request returns 400.

tagsstring[]

Tags for categorization and reporting. Stored on the message and propagated to Email Detail Records. Not returned in API responses.

template_idstring uuid
template_variablesobject

Variables for Liquid template rendering. Non-object values may cause a 422 validation error on message creation, but are silently treated as an empty object for template rendering.

text_bodystring

Plain text email body. Returned only by GET /email_messages/{id}; omitted from create and list responses.

Response

Message queued, scheduled, or sandbox-created.

Example response

{
  "data": {
    "recipient_statuses": {
      "bounced": 2,
      "delivered": 998
    }
  }
}

Changes

Changed in 7 of the 61 revisions of this API.63330

  • b1bf96d8391e1317See the full diff
    • ▲

      removed the required property data/inserted_at from the response with the 202 status

      response-required-property-removed

    • ●

      removed the optional property data/send_at from the response with the 202 status

      response-optional-property-removed

    • ●

      removed the optional property data/suppressed from the response with the 202 status

      response-optional-property-removed

    • ●

      added the new daily_limit_exceeded enum value to the data/events/items/type response property for the response status 202

      response-property-enum-value-added

    • ○

      added the new optional request property attachments/items/content_id

      new-optional-request-property

    • ○

      added the new optional request property attachments/items/disposition

      new-optional-request-property

    • ○

      added the new optional request property forward_of_message_id

      new-optional-request-property

    • ○

      added the new optional request property in_reply_to_message_id

      new-optional-request-property

    • ○

      added the new optional request property reply_to_all

      new-optional-request-property

    • ○

      added the new optional request property scheduled_at

      new-optional-request-property

    • ○

      added the new optional request property tracking_settings

      new-optional-request-property

    • ○

      the request property group_id became nullable

      request-property-became-nullable

    • ○

      request property send_at deprecated

      request-property-deprecated

    • ○

      added the optional property data/recipient_statuses to the response with the 202 status

      response-optional-property-added

    • ○

      added the optional property data/scheduled_at to the response with the 202 status

      response-optional-property-added

    • ○

      added the required property data/attachments/items/content_id to the response with the 202 status

      response-required-property-added

    • ○

      added the required property data/attachments/items/disposition to the response with the 202 status

      response-required-property-added

    • ○

      added the required property data/attachments/items/sha256 to the response with the 202 status

      response-required-property-added

    • ○

      added the required property data/attachments/items/size_bytes to the response with the 202 status

      response-required-property-added

    • ○

      added the required property data/attachments/items/url to the response with the 202 status

      response-required-property-added

    • ○

      added the required property data/created_at to the response with the 202 status

      response-required-property-added

  • 80833e66e0101See the full diff
    • ▲

      added RenderErrorResponse to the response body oneOf list for the response status 422

      response-body-one-of-added

  • 2fb3b617430a169See the full diff
    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 400

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 401

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 403

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 404

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 409

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 413

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the errors/items/code response property for the response status 503

      response-property-enum-value-added

    • ●

      added the new recipient_suppressed enum value to the oneOf[email_ErrorResponse]/errors/items/code response property for the response status 422

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 400

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 401

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 403

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 404

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 409

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 413

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the errors/items/code response property for the response status 503

      response-property-enum-value-added

    • ●

      added the new reputation_suspended enum value to the oneOf[email_ErrorResponse]/errors/items/code response property for the response status 422

      response-property-enum-value-added

    • ○

      added the optional property oneOf[email_ErrorResponse]/suppressed to the response with the 422 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 202 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 400 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 401 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 403 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 404 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 409 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 413 status

      response-optional-property-added

    • ○

      added the optional property suppressed to the response with the 503 status

      response-optional-property-added

  • 021f0faf96df11See the full diff
    • ▲

      for the header request parameter Idempotency-Key, the maxLength was decreased from 512 to 255

      request-parameter-max-length-decreased

    • ●

      changed the pattern of the header request parameter Idempotency-Key from ^(?:[A-Za-z0-9_-]{1,255}|"(?:[\x20-\x21\x23-\x5B\x5D-\x7E]|\\["\\]){1,255}")$ to ^[A-Za-z0-9_-]{1,255}$

      request-parameter-pattern-changed

  • b3c5aebde44c2133See the full diff
    • ▲

      removed the required property data/idempotency_key from the response with the 202 status

      response-required-property-removed

    • ▲

      removed the success response with the status 200

      response-success-status-removed

    • ●

      removed the request property idempotency_key

      request-property-removed

    • ●

      added the new 10027 enum value to the errors/items/code response property for the response status 400

      response-property-enum-value-added

    • ●

      added the new 10027 enum value to the errors/items/code response property for the response status 401

      response-property-enum-value-added

    • ●

      added the new 10027 enum value to the errors/items/code response property for the response status 403

      response-property-enum-value-added

    • ●

      added the new 10027 enum value to the errors/items/code response property for the response status 404

      response-property-enum-value-added

    • ●

      added the new 10027 enum value to the errors/items/code response property for the response status 503

      response-property-enum-value-added

    • ●

      added the new 10027 enum value to the oneOf[email_ErrorResponse]/errors/items/code response property for the response status 422

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the errors/items/code response property for the response status 400

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the errors/items/code response property for the response status 401

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the errors/items/code response property for the response status 403

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the errors/items/code response property for the response status 404

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the errors/items/code response property for the response status 503

      response-property-enum-value-added

    • ●

      added the new 10036 enum value to the oneOf[email_ErrorResponse]/errors/items/code response property for the response status 422

      response-property-enum-value-added

    • ○

      added the new optional header request parameter Idempotency-Key

      new-optional-request-parameter

    • ○

      added the non-success response with the status 409

      response-non-success-status-added

    • ○

      added the non-success response with the status 413

      response-non-success-status-added

    This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 6ef0ae248bf71See the full diff
    • ○

      endpoint added

      endpoint-added

    This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 224ed0d8a5c31See the full diff
    • ▲

      api path removed without deprecation

      api-path-removed-without-deprecation

    This revision also has 111 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog