MacOS Mojave - Apple Mail wasting bandwidth moving phantom messages and drafts

Best guess was some part of the Mail.app went rogue, but that's only a guess. New Admin acc't solved it (with new Mail), but migrating all into a new OS did not. Swapping years of stuff between Admins is not much fun; I suspect replacing the Mail.app would have solved it, too, if the app had been available. At least I got some housekeeping done along the way.

Used new Mail.app to import all "On My Mac" boxes, so the problem wasn't lurking in there. Network activity is back to normal. Hope it stays that way.

Thank you for your patience, suggestions, knowledge and assistance, BD. Wish I had a better answer for you.

Migration to new OS on new drive didn't fix it. Problem came along.....

So, looks like I'm moving to a new Admin acc't - the hard way - starting with a new Mail acc't, test, import "on my Mac" boxes, then a long overdue house cleaning. Will try to find cause along the way. Dang! Didn't expect this.

Good to hear from you again BD, thank you for picking up my post!

I’ve swapped Drafts (and others) back and forth between On My Mac and ATT a few times with no change, but I just set it back to OMM as you suggested. Rebuilding boxes (when available) doesn’t seem to change anything. Only one account, IMAP, only one machine online via Ethernet.

Booted in SafeMode, my network monitor is MIA (naturally), but I have Activity Monitor > Network open. At top of list is Mail, and I’m watching Sent Bytes tick up from 7MB to 10MB to 28MB to 30MB in 3MB increments, with no end in sight. Just passed 64MB and counting. Sent Packets also counting up, past 25,000, past 30,000…. Rec’d is relatively static.

All I did was open Mail (in SafeMode). Bottom of Mail window is stuck on “Saving 1 of 172 Drafts - 3.6MB”

Network Activity dropped to below 50MB (when I wasn't looking), now counting up again in 2-3MB increments. 60MB, 70MB… Sent Packets now passing 50,000 (no apparent decline there).

Graph at bottom of Activity Monitor shows packets in ~ 40,000 @ 30/sec, packets out ~ 56,000 @ 45/sec.

Quitting Mail hangs for too long….

Relaunch, Sent Bytes counting up again from 3MB, Packets from ?K, past 48MB and 12,000 in no time.

Mail’s IMAP log file is 6.2GB - sorry I looked….

Mail on the iPhone is normal. Would axe entire Mail.app and start over, if I could replace it. It’s all but unusable at this point. Worse, it drags down bandwidth when open, to the point that a simple post to a discussion group times out. (Normal = 2.5M at best - but, hey, I know a guy who's still on dialup ;-)

Restart, setting boxes back to ATT, as soon as I quit Mail.app, network activity drops from 8K/sec to zero. Will be deleting that gargantuan log file next. Can't even open Mail until I can get it under control....

EtreCheck report turned up nothing we don't already know - found some ancient Adobe Switchboard file running from <private> that is gone now, no other surprises. Glad to see it's no longer free; version I have (5.1) requires purchase to unlock detailed reports (so I can't burden you with those), but its basic functions are still quite informative. FWIW, I spend a lot of time removing junk from other peoples' Macs and keep mine pretty clean. Reed's MalwareBytes went commercial when he sold it, think it's primarily a browser tool. That I don't have.

Can't discuss machine here (!) other than OS. Installed the latest Mojave update (after backup), but had to use cellular to do it. Downloading via Software Update on computer timed-out 6 times before I found Mail.app issue.

Deleting the 6.2GB Mail log file appears to have been harmless (was in same Data folder we replaced).

Anything from Terminal that might shed some light?

Might create a new Admin acc't and see if I can make new email with same address. Otherwise, replace the whole OS? Groping in the dark here. Really appreciate your wisdom and help BD.

Yup, that did it. Even got your message while on new email acc't. Wow, what difference! Question now is, will problem import to a new OS with everything else? Standby...

Wish we could (openly) discuss specs, but you probably know by now, huh. One odd effect since hotrodding the MacBeast here comes from logging into sites like PayPal, eBay, etc: Without fail, I get the "new device detected" message. Every time.

No wiser re the Mail.app issue (haven't seen any other reports, either), but of any/all help available, you'd be the one to take it on. You have ALL my respect for what you accomplish here. Will get on with new drive/OS and report back.

1,000 thanks, again, BD

No Outbox (nothing pending), Connection Doctor is green x2 (eventually).

Clicking the Show Details button produces a seemingly endless scrolling list of gibberish. Scrolling, scrolling, got to the bottom of it and took screen shot as fast as I could (below). You can tell by size of scrollBar that there’s a whole lot more above that. Almost expected screen shot to have motion blur.

Activity window is typical - two empty progress bars - shown here over bottom of Activity Monitor window while in SafeMode doing nothing (I think).

Found "New Folder with Selection" option in the File Menu.

So now I have “New Folder With Items” containing plist and Data folder.

Data folder is from June of 2020.

The Container.plist file has a created/modified date from just three days ago with 600 lines of gibberish:

After restart, I now have new Container.plist with same 600 lines as above, a new Data folder with same aliases as old one.

New aliases are folder icons, old ones were generic dog-eared icons - only change I can see.

Old files still present within “New Folder With Items.”

Mail is behaving the same, still saving 1 of 172 drafts, moving 1 of 12 Messages w/o progress, hogging bandwidth as before.

Same wildly scrolling gibberish in Connection Doctor > Show Details. No change. Russians? NSA? Why me?? @#%$&!!