Twilio SendGrid message ID
Marketing. A unique identifier that Twilio SendGrid generates and assigns to an email message for event identification purposes.
Twilio SendGrid assigns this ID to individual email messages. You can search for this Message ID information in the Activity Feed as well as Event Webhook POST data. The Activity Feed labels the Message ID as Message ID and the Event Webhook labels it with sg_message_id.
Example SendGrid Message ID: XBg2anf2TqCy6WXKQFhieQ.filter0905p1mdw1-4434-59E0C6FF-3.0
(information)
What the Twilio SendGrid Message ID isn't
The Twilio SendGrid Message ID differs from the SMTP headers: X-Message-ID and Message-ID.