Why does Gmail returns 2 attachments for a message when ics file is attached?

Gmail is treating these as separate attachments because MIME types specify the nature and format of the content. Even though both attachments might represent the same iCalendar data, they are technically distinct due to their MIME type classification. This behavior ensures that the recipient (or the email client) can interpret the attachment correctly based on its declared type.

Example:

Response from endpoint /message for Gmail returning two attachments:

        "attachments": [
            {
                "is_inline": false,
                "id": "v0:aW52aXRlLmljcw==:dGV4dC9jYWxlbmRhcjsgY2hhcnNldD0iVVRGLTgiOyBtZXRob2Q9UkVRVUVTVA==:1773",
                "grant_id": "4f20cb03-4c3a-4050-b03d-ec1f60a4ab0e",
                "filename": "invite.ics",
                "content_type": "text/calendar; charset=\"UTF-8\"; method=REQUEST",
                "size": 1773
            },
            {
                "is_inline": false,
                "id": "v0:aW52aXRlLmljcw==:YXBwbGljYXRpb24vaWNzOyBuYW1lPSJpbnZpdGUuaWNzIg==:1773",
                "grant_id": "4f20cb03-4c3a-4050-b03d-ec1f60a4ab0e",
                "filename": "invite.ics",
                "content_type": "application/ics; name=\"invite.ics\"",
                "content_disposition": "attachment; filename=\"invite.ics\"",
                "size": 1773
            }
        ],

Those attachment is break down as:

• text/calendar attachment:

  • Content Type: text/calendar
  • Filename: invite.ics
  • ID: 757iv7g2p23zfxedwla1lxhtd
  • Size: 1773 bytes

• application/ics attachment:

  • Content Type: application/ics
  • Filename: invite.ics
  • ID: av996ptwmzbl0d1xov57hfzdq
  • Size: 1773 bytes

• The first attachment is identified with the MIME type text/calendar.
• The second attachment is identified with the MIME type application/ics and has a specified filename (invite.ics).

In many email clients and services, including Gmail, attachments are identified and processed based on their MIME types. In this case:

• Both attachments likely contain the same content (an iCalendar file, typically used for calendar events).
• However, Gmail identifies them as two separate attachments because they have different MIME types (text/calendar and application/ics).

Updated July 10, 2024 13:44