We have experienced a very strange issue and we cannot really put our finger on it - maybe someone else has seen this too, so please let me know in case we can find a way to reliably reproduce it.
The problem started with a user claiming that the sent date on their emails has changed to today. This seemed utterly impossible and we had no way to reproduce it. We were 2 SM builds back at the time. However, a week ago another user complained about the same thing.
And today I also think I experienced it and it may be due to this: I have a large mailbox (30+ GB) which is synced with MS Outlook Pro Plus 2019 via MAPI. In this mailbox I had a large folder (13.000+ emails) which I cleaned up and moved to subfolders like this:
I made all of the modifications in WebMail (created new mails, moved emails). After a while, the new folders appeared in Outlook and emails in the subfolders started appearing as well. However, the LargeFolder still showed 13.000+ emails after leaving Outlook to sync for a few days - it did not start to mirror what I have in WebMai. During this, syncing other folders is unreliable as well (usually it works without issues).
Today I go to the WebMail to the LargeFolder which now it still has some 3000 emails left, but I can see that emails disappear and appear back, but with a different sent date - that of today. And I can see that going back many of the emails have been modified like this. I`m sure the date is wrong because all of the emails in this folder are from an automated notification system that timestamps each email, so the timestamp in the body of the email does not match the receive date that appears in WebMail.
As you can see above, the date that appears in Webmail is today at 10:08 AM, when in fact the mail has been sent by the system (and received imediatelly, it`s a local system) on 26.11.2020 @ 14:55 PM
If we look at the Header of this same email, the time is correct:
Then why does Webmail (and Outlook - they both show the same) show the incorrect time?
Note that all that reported this had Outlook synced via MAPI.
I was able to stop the behavior (I released that Outlook was going slowly email by email and changing them..) by right-clicking the folder in Outlook, clicking Properties then Clear Offline Items.
We have a user that needs to prove they sent emails at a specific date (some regulatory obligations) and now they are complaining they can no longer to so due to the date and time that now appears on the emails.
Let me know if anyone else has experienced this.
@SM: is this something that is known?
EDIT: updated the post to correct the fact that we were using Outlook synced over MAPI.