Email · Website glossary

Message-ID

Quick answer · What is Message-ID?

A message header field intended to identify a particular version of an email message.

IN PRACTICE

Message-ID: an example

A support team uses a Message-ID together with time and recipient to locate a delivery event.

KEEP IN MIND

A Message-ID is not a password or proof of delivery; it is one piece of investigation context.

Put the idea to work

Frequently asked questions

What is a practical example of Message-ID?

A support team uses a Message-ID together with time and recipient to locate a delivery event.

Does a Message-ID prove that an email was delivered?

A Message-ID is not a password or proof of delivery; it is one piece of investigation context.

Which concepts should I read alongside Message-ID?

Email header: A structured field in a message carrying information such as its sender, recipient, subject, or transport history.
Email bounce: A delivery failure notification generated when a message cannot be delivered as expected.