Subject: Meeting invite
From: Alice <alice@example.com>
To: Bob <bob@example.com>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary=alt

--alt
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

Team sync invite
--alt
Content-Type: text/calendar; charset=UTF-8; method=REQUEST
Content-Transfer-Encoding: 7bit

BEGIN:VCALENDAR
VERSION:2.0
METHOD:REQUEST
BEGIN:VEVENT
SUMMARY:Team Sync
END:VEVENT
END:VCALENDAR
--alt--