Message-ID
A unique identifier header usually generated by the sending mail system.
Why it matters
The Message-ID domain can add context about where a message may have originated.
Example pattern
A message from a brand has a Message-ID ending in an unrelated domain.
How CheckLink can help
CheckLink can flag simple Message-ID domain mismatch signals when parsing headers locally.
Related terms
Related guides
Check the signal in context
Security terms are useful, but real decisions need context. Use CheckLink to inspect available signals before you click.