Get a message attachment

Downloads the attachment at the zero-based index in a message's text.attachments array and returns its decrypted bytes with the media type the attachment declares. A declared PNG, JPEG, GIF or WebP type is kept only when the bytes match it; a missing, malformed or mismatched type returns application/octet-stream. The Content-Disposition header carries the original filename. Works for attachments a customer sent and for attachments you sent. For a received attachment, message_id is the message.id of the amb.received webhook event, and index is the attachment's position in that message's text.attachments array.

Apple retains an attachment for about 30 days; availability after that period is not guaranteed, so download an attachment when the message arrives rather than on demand later. An unknown message or index returns 404; an attachment Apple no longer holds returns 503.