Mail App Keeps Deleting & Redownloading Messages

[rosalita2]

In a nutshell: I'll open my computer, and I see my Mail app connect to the wi-fi and update. For example, it'll go from 20 unread to 110. Then, sometimes after a while and sometimes right away, that number will tick all the way back down to around 0. It mostly affects one email (my personal one, my work one will sometimes be a bit affected but never as bad as my personal one which I've been using since 2012).

What's happening is its deleting old emails, then deletes newer and newer and newer until emails I received this morning are gone. But weirdly my much older emails are left untouched - so suddenly the top of my inbox is emails from April 2021.

Then it starts "Downloading Messages: 441 of 35,603" .-.

I started a new system of using Smart Mailboxes to sort different types of emails between my personal and work accounts a few months ago, and it's been great, and now it's extremely frustrating that I have to go on my phone or desktop version to look at and send emails.


I have a hunch that it is only happening on certain wi-fi's but it's happened sporadically on some wi-fi's I thought were "safe" from it so...

I've tried a few solutions I've seen online, like moving drafts to on my computer, but didn't do anything, and I don't think that's the issue in my case anyway - I haven't seen any other issues that is this specifically, which is very clearly deleting and redownloading emails. Any help is much appreciated - it's driving me crazy.

 

[Koinu]

Very interesting. I'm having a similar problem, but only since upgrading to Monterey. I have completely deleted and re-added all mail accounts, with no change in behaviour. Mail opens, shows me all my mail, but then says "Downloading Messages 1 of 345,000... etc." It seems to be primarily related to Exchange accounts that are part of an on-premises (i.e. not office 365) system we use at work. I cannot easily confirm whether it's doing it for my GMAIL account also.

I got to a point where I thought it had quit -- I no longer saw the Downloading Messages indication, and the network monitor (Little Snitch) seemed to be quiet. (Previously, it showed steady download network traffic for Mail on those Exchange domains.) But then Mail started doing it again. The only thing I could think MIGHT be implicated is that I do sometimes use a VPN -- (Windscribe, to be specific), and after I had been using that VPN, the whole Mail download process started again.

There are not sufficient logging/diagnostic tools to help understand WHY Mail is doing this, but it is profoundly annoying - especially since for the next few weeks I'm on a bandwidth-limited internet connection, and have already consumed most of a month's allotment by the 10th of the month...

If you (or anyone else reading this thread) can help identify WHY Mail is doing this, and specifically what needs to be done to make it stop, this would be MOST helpful!

I can confirm that I have:
- upgraded Mail from Big Sur (original situation); this started the undesirable re-downloading behaviour on Monterey;
- Rebuilt Mailboxes (from within Mail), which is supposed to effectively "start over" with re-downloading messages;
- had problems with search not finding anything newer than about a month old;
- deleted the Envelope files from Mail, forcing it to "Upgrade" things when it next started;
- seemingly fixed the search issue, since spotlight and mail search now show me all relevant messages;
- completely deleted and re-added all mail accounts (including actually deleting the folders from /Users/.../Library/Mail);
- seen Mail STOP doing this for a period of a few days (confirmed with Little Snitch no longer showing constant traffic);
- had this start up once again, possibly after having used the Windscribe VPN;

Any insight/thoughts most welcome!!!

Regards,
Scott