me.message

Add file attachment

Changed on Jul 17, 2026

Use this API to add a file attachment to a message. An attachment can be one of the following types: fileAttachment, itemAttachment, or referenceAttachment. All these types of attachment resources are derived from the attachment resource. For file attachments smaller than 3 MB, use this endpoint. For larger files, use the createUploadSession endpoint.

post/me/messages/{messageId}/attachments

Request

Base URL
https://graph.microsoft.com/v1.0
Auth
OAuth 2
Authorization codehttps://login.microsoftonline.com/common/oauth2/v2.0/authorize
Client credentials
Token URLhttps://login.microsoftonline.com/common/oauth2/v2.0/token
ScopesMail.Read, Mail.ReadWrite, Mail.Send
TypeScript
https://skmtc.dev/ballerina-platform/apis/microsoft-graph-mail-api/docs/me/messages/:messageId/attachments/post.ts
A function with typed inputs. Its response is checked against the schema.

Request body

@odata.typestring

idstring

The unique identifier for an entity. Read-only

lastModifiedDateTimestring date-time nullable

The Timestamp type represents date and time information using ISO 8601 format and is always in UTC time. For example, midnight UTC on Jan 1, 2014 is 2014-01-01T00:00:00Z

sizenumber

The length of the attachment in bytes

namestring nullable

The attachment's file name

isInlineboolean

true if the attachment is an inline attachment; otherwise, false

contentTypestring nullable

The MIME type

contentBytesstring base64url nullable

The base64-encoded contents of the file attachment. Required only for file attachments

Response

Created attachment