delayed emails

dear All,
one of my end users claimed that he received an important email on old date. is there any way to verify the received date of a specific email on Kopano server?

In the “internet head lines” you can see the history of the e-mail transfer. If it was stuck somewhere you see if it’s in your own infrastructure or external.
In Kopano you can check flow in the log files dagent.log/spooler.log and the MTA (mail.log or syslog)