Mail app - stuck downloading and not syncing properly

[CHI-M]

So I've been having issues with my Mail app acting up since prior MacOS sequoia. I updated to Tahoe thinking it may have finally fixed issues.

I only sync my iCloud email. My Mail app just gets stuck downloading, if I close the app, it stays active with the "dot" icon in tray of like several mins before quitting.

I tried to turn off account, and re-add thinking it would rebuild but maybe there are other ways to figure this out?

Been pulling my hair on this for last 6/8months. iPad and iPhone mail app works fine.

One thing, my Mail app inbox says 4609messages, while my iCloud website inbox has 4611. as if there are 2 messages breaking this whole thing?

 

[GFS]

I've had similar issues over a couple of years, which I think were associated with an old Mac, that finally died and which I'd used for AppleSeed (back in the day, when it was still a 'secret' thing) and which had created iCloud problems for my very very old dotMac account. Because the Mac was no longer working, I couldn't remove it from iCloud via the Mac itself. So... a couple of days ago:

3 things you can try:

• Rebuild the mailboxes: Select the mailbox / Menu - Mailbox / Rebuild
• Force reset Mail: Restart Mail holding down the Shift key.
• Ensure that iCloud is working fully: Does the Mac appear in Find My / Devices (on the AppleID website too)?
This can be hard to fix and somewhat surprisingly, after trying to fix what was similar to what you're describing, plus problems with Smart Mailboxes refusing to be deleted or edited... with Tahoe I found that the Mac wasn't working for Find My. It wasn't included as one of my devices. I tried all the obvious things to get it working.. turning on/off, logging out/in from iCloud etc. What worked in the end was running Disk First Aid from Recovery Mode. Now... it could have been coincidence, that after all my attempts, it would have started working anyway and running Disk First Aid actually had nothing to do with it, but it's worth a try.

 

[markgpearse]

I had a similar problem in the past and now have it again after installing Tahoe. When I open the Mail app on my MacBook Air, I get a "Downloading Messages" message at the bottom of the left side column. There is a horizontal blue bar that goes back and forth as it downloads mail. It doesn't impact my mail, it's just annoying.