[RESOLVED] Duplicate messages received in Thunderbird

[Qqmike]

Have used T-Bird forever. This just started yesterday.
T-Bird keeps sending me messages -- emails -- (from Centurylink webmail) that it has already sent me, and that I have opened.
This morning, it sent me messages it had already sent me several times yesterday.

What I've done*:
Tried deleting popstate.dat file (from the account subfolder in the "Mail" folder in my profile folder).
Tried deleting the Inbox (after backing up its contents to another subfolder).
Tried deleting BOTH the "Inbox" and "inbox.msf".

I do NOT wish to do this:
go to "Tools -> Account Settings -> Server settings", and uncheck "Leave messages on server."

Note:
I use Centurylink. Centurylink has upgraded its webmail email. The timing of this suggests some corruption could have entered the picture here (corruption in my Inbox or profile folders). But It is only my suspicion.

Any ideas would be appreciated.

* References
http://kb.mozillazine.org/Duplicate_messages_received
http://kb.mozillazine.org/Compacting_folders#Real_fix

[Snowhog]

Have you examined the email settings on your Centurylink account?

[Qqmike]

I think so, Paul. What to check in particular?

The Server settings are correct (pop3 etc.)

I will mention that this problem only occurs on my desktop PC with 20.04 + T-Bird.
It does not occur on my phone or tablet (both of those use a Samsumg email client from the Google App store.)

[Snowhog]

Have you attempted the 'last' resort?

As a last resort, you can try creating a new profile, setting up your accounts in it, and then migrating your mail and address books over from the old profile.
Of course, if you try deleting files or making a new profile, it's wise to first make a temporary backup of your mail and settings.

[Qqmike]

Have you attempted the 'last' resort?

No. But as I posted the OP, I thought about it, but dared not say it!

I need to keep my mail folders with all their past contents, and I could migrate those (by simply drag and drop into the new profile).
The "last resort" would ensure there's no corruption in, mainly, that Input folder or those various temp folders.

If no sure-fire thing pops up here, I'll do it. In fact, uninstall and re-install T-Bird.

Thanks, Paul.

[Qqmike]

This is gonna be one of those "watching waiting" cases.
Yesterday, I got a couple hundred duplicate messages, sometimes 3, 4, 5 copies of a message.
188 duplicates came in all at once at 3 pm yesterday.
Now today, so far, at 11 am, the problem has not occurred yet.
It may have been experienced by others, reported, and fixed by ... someone.
I'll hold off for awhile before marking this Solved ...
(I did not yet do anything on my end, btw.)

[Qqmike]

Yep, looks like the problem cleared up on its own. A problem somewhere, maybe at Centurylink, maybe with Thunderbird, or elsewhere (servers etc.).