Email bounce, then opened?

[Joshenser]

Has anyone had any instances where an email has bounced, the status hasn't changed to delivered, but then has been marked as opened?

I am intrigued to know how this may be the case.

Thank you!

[SanfordWhiteman]

A mailserver can choose to give a rejection response (5xx) while actually accepting and/or quarantining the email, and the email can eventually be released from quarantine and opened.

For example, our mailserver allows a message to be copied to a folder while telling the sender it was rejected: