Archive for October 11, 2019

Friday, October 11, 2019 [Tweets] [Favorites]

Mail Data Loss in macOS 10.15

I’m working on more posts about the Catalina release, but I wanted to start with a short warning. I’ve heard a bunch of reports of data loss in Apple Mail. Thankfully, none seem to be caused by my apps. (Ironically, one of the bugs I’ve encountered is the inability to delete messages via AppleScript.) And, in fact, most of the damage has occurred without my Mail plug-in even being installed. Nevertheless, people contact me because it’s not unreasonable to wonder if third-party software is to blame, and I also hear from people who want a second opinion because what Apple support told them didn’t make sense.

What I’m hearing:

I don’t know whether these are due to Mail bugs or to other factors such as problems on the Mac or with the mail server. But my advice is to hold off on updating to Catalina for now. These sorts of issues are pernicious because:

  1. You may not notice that anything is wrong unless you are looking at the particular mailbox or messages that are affected.

  2. Because the data is synced to the server, problems can propagate to other Macs and iOS devices.

  3. Making a backup is difficult because, even if you set the preference, Mail no longer automatically fully downloads all messages. So the backup of the local data will necessarily be incomplete. (See EagleFiler’s Importing Attachments instructions for more about this. I’m happy to have most of my mail archived outside of Mail.)

  4. Restoring a backup is difficult because Mail data is constantly changing. There is no straightforward way to merge restored data in with messages received since the last backup, and also with the live data on the server.

Of course, it’s good to make backups anyway.

Apple advisors are apparently telling customers that if Mail data gets lost on Catalina, it can’t be recovered from a Time Machine backup that was made using Mojave. This didn’t make sense to me, and I’ve verified that it’s not the case. You can use Time Machine to get at previous versions of the folders in Mail’s data store, and then use the File ‣ Import Mailboxes… command to selectively import them into Catalina Mail. Since they import as new, local mailboxes, this shouldn’t affect messages that are on the server.

I also think that the advice to restore the whole Mac to Mojave makes no sense because as soon as you launch Mail it’s going to delete all the messages that were deleted on the server. In order to actually restore them, you have to make copies of the messages that might have already been deleted. That’s what Import Mailboxes does.

Update (2019-10-11): See also: Howard Oakley, TidBITS, Hacker News.

Update (2019-10-12): See also: MacRumors, iMore.

Update (2019-10-13): See also: AppleInsider.

Update (2019-10-14): Commenter Shiner says that the lost messages from “updating Mail’s data store” happens for local mailboxes every time Mail’s database is rebuilt, not just when migrating from Mojave, and reported this to Apple in August. It’s “trivial to reproduce” and lost 160,000 out of 200,000 messages in a test.

There’s some evidence that the moving messages issue is related to Microsoft Exchange accounts.

Peter Steinberger:

A doctor friend of mine lost about 20.000 emails when he upgraded to iOS 13. It was a POP3 account.

See also: TechRadar.

Update (2019-10-15): I’ve received four reports that messages moved to an iCloud mailbox (that were not originally in that iCloud account) simply disappear instead of showing up there. At first, we thought this was a Catalina issue, but it also seems to be happening with High Sierra now. My guess is that it’s an issue with certain of the iCloud servers.

Update (2020-01-29): macOS 10.15.3 fixes one of the bugs but not the others.