A curious problem with my own Zimbra account means the time of all my outgoing messages appears to be offset by around 1hr 20 mins.
When I send mail in from a different mail client (on the same machine) the sent time is correct but my Zimbra GUI reports the received time with the funny offset.
I've checked bios time and localised time in the desktop's OS and there appear to be no errors. My other apps all report the right time.
Other people using the same ZImbra server and domain don't see the problem except they report my messages are displayed out of sequence in their inbox due to the time offset.
The offset is not a whole hour but rather 1 hr 23 mins 16 secs - to be precise