Mail on my iMac Pro (Sonoma) has suddenly ballooned to occupy 1.19 TB of my 2 TB SSD, causing all sorts of headaches with “disk full” messages. (Storage claims I have only 30 GB available). The same mail setup on an Air (M1 2020, also Sonoma) linked to the same server (I believe gmail, our laboratory contracts Google to handle its mail) “only” occupies 70 GB.
I have no idea what happened, or how to recover the obviously wasted space in my desktop machine.
Check that logging didn’t get turned on by accident. Mail > Window > Mail Connection Doctor. Uncheck Log Connection Activity, then search for the logs and delete with Show Logs.
Thanks for the hint. Alas, “Log Connection Activity” is unchecked, and “Show Logs” displays an empty folder named “Diagnostics”
Next thing I always try is to delete the account in Settings, clean out the Mail cache folders, then add it back in
Can this be done without losing messages?
Yes, as long as you’re not using POP. If you are using IMAP, and have access to Webmail you can check that all your messages are on the server.
Thanks Tony. For now Mail on my Air works well. I will need to brush up on the Take Control of Mail that I have skimmed through in the past. I don’t think it addresses my particular problem, but may help in the steps of trashing what’s there and rebuilding the setup without losing information. I’m pretty sure I have an IMAP setup but need to confirm.
Cheers
Jose
What file type is hogging your disk? One single (growing?) file or many files of various type? Is the growth restricted to one area in the file system (i.e. it’s all within one folder and below)? The simple but excellent and free Omni Disk Sweeper will let you see what’s taking over your disk and help answer those questions. Frankly, I have never seen an IMAP account come close to taking up TBs of space so I wonder if a mail acount (or Mail.app itself) is actually really the culprit.
Hi Simon: This is what happens when I try and send an email from the iMac.
Jose
so of course it works now.
Simon: Thanks for the interest and suggestions.
I too am surprised (and quite frankly horrified) by this turn of events. All I know is that the “Storage” thingie in Systems Settings, screen shot attached, indicates the offending data type is Mail.
The execution of the mail program on the iMac is also giving problems. I can receive emails, but cannot send. I (usually) get a message that says "cannot send message using the server Gmail” or asks me for password for user “”. So of course when I try to demonstrate this it works properly. Go figure. It’s flaky for sure.
I have an Air that is working fine, connects to the same server, and has only 70 GB of files attributed to Mail. This message I’m typing on this platform.
I need to trash (safely) the mail system on the iMac and rebuild it, but I don’t want to lose the messages that go back 10 years or so. My principal accounts seem to be IMAP so I guess this is less risky. But what happens to an IMAP message when it is deleted? Is it erased from the server?
Thanks for the suggestion of Omni Disk Sweeper, I’ll look into it.
Jose
When I use AppCleaner and drag the Mail app to the trash, that clears out all of the caches and logs and every ancillary file that Mail uses. It does not, of course, delete the Mail app. All of my accounts use IMAP and I’ve never lost any email.
Oh, that will delete the rules you’ve created. I’d setup rules in the webmail interface of your email accounts instead; then the rules results will be available to all the places you’ve attached your IMAP accounts.
One more idea - boot into the recovery console, and select ‘reinstall operating system’. This frequently cleans up corrupted files without making any changes to user files or downloading Mail.
I don’t think these days that will do much for most problems.
Because of the SSV and the way macOS boots on Apple silicon Macs, if you can log on to your user account that means macOS has already been able to verify that every piece of the system matches exactly what Apple says it should and how it was initially installed ro updated. The exception being few items like Safari that have been relegated to remaining outside the SSV (presumably to facilitate updates).
These days, if your macOS suffers just a single bit failure (think infamous cosmic ray event) — even within a piece of code that never gets loaded on your system — that should prevent the system from booting entirely. At that point you’d need to reinstall through Recovery.
I think what would make more sense in such a case where there appears to be an issue in user land, is to set up a brand new account and see if the problem goes away. If it does, piecemeal manual migration (which admittedly can be a real pain) should allow you to regain a stable working environment.
Have you tried Mailbox > Rebuild ? It reconstructs the mail database. Might be helpful.
This happed to me as well during macOS beta testing, and I apologize but I cannot remember how I solved it. Apple apparently did not fix it from my report 
. I do know that I solved this by starting with…
The file system is the achilles heel of unix hence macOS past Mac OS 9. Cache corruption and the resulting malfunctions are just one of the side effects of the file system liability; and caches get corrupted constantly in macOS.
Check file sizes here and anything inside these folder can be trashed at will:
Mail will rebuild the stuff in here, so you can delete the contents and then run Mail:
This should be empty:
If you sync with iCloud for your Address Book, then you can trash what is in here:
Lastly, check your mail downloads for absurd disk usage here:
