Download a message attachment
Streams one attachment from a message through the authenticated endpoint. Attachment metadata also provides short-lived download URLs for clients that cannot set request headers. Supports standard byte ranges.
Authorizations
Sendmux API key. Use a root API key for Management API routes, or a mailbox credential for Mailbox API routes. Obtain keys from the dashboard under API Keys.
Headers
Optional byte range, for example bytes=0-1048575.
Query Parameters
Mailbox public ID to target when the credential grants access to more than one mailbox. Omit when the credential is scoped to exactly one mailbox.
Short-lived token embedded in attachment metadata download_url values. Clients normally fetch the full URL rather than constructing this parameter manually.
Response
Attachment bytes