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Beware Mail Data Loss in Catalina

Mail 13.0 About boxMichael Tsai, the developer of the long-standing SpamSieve plug-in for Mail on the Mac, has written a blog post warning about potential Mail-related data loss when upgrading to macOS 10.15 Catalina. In particular, he’s hearing from numerous customers that updating Mail’s data store from Mojave to Catalina sometimes says that it succeeded, when in fact, large numbers of messages turn out to be incomplete or missing entirely. Plus, moving messages between mailboxes on the Mac can delete message bodies, leaving only headers. If you moved the message to a mailbox on the IMAP server, other devices see it as deleted, and that deletion status eventually syncs back to the original Mac, where the message disappears as well.

As Michael Tsai points out, these problems can be difficult to notice (if you’ve already updated to Catalina, run through your mail to see if it has been affected), the problems can propagate to other devices, it’s difficult to make a complete backup, and even if you have a backup, it’s hard to restore.

To reiterate our advice in “macOS 10.15 Catalina Ships, Upgrade with Caution” (7 October 2019), hold off on upgrading to Catalina for a while, particularly if you use Mail.

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Comments About Beware Mail Data Loss in Catalina

Notable Replies

  1. Using Mail with Gmail, IMAP always behaves a bit strangely; and Mail under Catalina does add a few more quirks. The main one I’m seeing is that a mail item moved from one mailbox to another copies rather than moving, leaving the original to be manually deleted. Annoying but not fatal— I’m not losing any mail bodies, I’m glad to say.

  2. It’s worse than that, because you should be able to specifically target the Data volume to fix whatever problem led you to fsck in the first place, and the Mac-Enterprise list indicates that doesn’t work either. (And in theory, the read-only volume should have no such problems, so it’s there or something else entirely.)

  3. I recommend Mail Steward for archiving emails before a major OS update. It stores emails in a MySQL database that cant be touched by the OS installation. I have emails going back over 15 years.

  4. No data loss here, but a different problem: out of application memory crashes when Catalina was upgrading its Mail from my Mojave installation. Running 16 GB RAM, that shouldn’t happen but with Catalina it did. Reason: I have nearly 20 years of old emails stored in mailboxes “On My Mac.” This is the first upgrade when I’ve run into the problem. I did find a work-around that I’d be glad to share if anyone wants to know, but I’m also looking for a solution that would keep some of those emails outside the Mail program without turning them into textfiles while having them ready to bring back into Mail in Catalina and future Mac OS as well.

  5. PS: Mail Steward could be the longer-term solution I’m looking for, of course. I’ll check it out.

  6. Wait… is this the opposite of Sherlocked when a OS upgrade makes a 3rd party app more necessary?

    This app has been stewarded by Apple.

    Thanks Apple.

  7. Catalina has also introduced the issue where 3rd party programs (such as HoudahSpot or BusyContacts cannot search Apple Mail. (I have registered my view on For this reason I am researching 3rd party mail programs such as Mailmate or Postbox. Any opinions or comments on what 3rd party mail apps are worth looking at… Thanks

  8. I swear by InfoClick. Use it multiple times every day.

  9. I have to admit, I’ve never had a problem searching for mail and my email, stored in mail boxes on “on my mac” goes back decades.

    What problems occur that require a 3rd party search engine for mail?


    Al Varnell

        October 16

    Any opinions or comments on what 3rd party mail apps are worth looking at…

    I swear by InfoClick. Use it multiple times every day.

  10. David, I agree, Mail search is very good. But I like HoudahSpot as it allows me to create a search then save it to the Finder (like a smart mailbox). I have lots of these, which I can then search for. I don’t think I can do this with Smart Mailboxes in Apple Mail (also when you have 100s of smart mailboxes it gets a bit messy!)

    Thanks Al for InfoClick I’ll check this out as it appears to build its own index (so independent of Catalina’s restriction). I could not tell if it allows me to save a search to the Finder & then run the search by launching from the Finder (I’ll download the trial & test this…)

  11. DEVONthink Pro will archive individual emails, entire mailboxes, or multiple mailboxes with a single menu command. They remain in EML format, as originally organized, with all metadata including MailTags. You can update the archive whenever you wish and DTP will not import duplicate UUIDs. Anything indexed in DTP is also indexed in Spotlight, unless you opt out. Of course, DTP will also file your other documents and perform all sorts of tricks. 15% discount for TIDbits members.

  12. Infoclick won’t work with Catalina Mail, since as noted elsewhere here Spotlight searching access has been disabled by Apple. That’s a problem for other non-Apple programs like Houdah Spot as well. Really stupid; I don’t see the point of that “feature.”

    Mail in Catalina has been awful for me. Tons of random re-downloads. And it lost and continues to lose all local “On My Mac” folders, even after I re-imported them.

    So I’m looking for a replacement; tired of Apple’s buggy junk. Looking at old dependable Thunderbird right now.

  13. I’m having no issues whatsoever with InfoClick in Catalina. I don’t believe it has ever used the Spotlight database, rather it builds it’s own which is far faster with multiple means of search. It doesn’t appear to have anything to do with Catalina Mail. It’s a separate app, not a Mail extension of any kind.


  14. I’ve seen several reports ‘round the net that Catalina Mail has some issues that sometimes delete mail in the Inbox. Googling tells me that it’s mostly for those that use gmail although not in so many words.

    Is there any reliable info regarding the issue, what’s affected and the like or are we mostly waiting for Catalina.2 to be issued and hope that fixes it? I’ve held off so far on upgrading.

    I do have a gmail account but it’s not primary…heck, it’s not even tertiary. My main mail accounts are my original account at, iCloud, and at FastMail.


  15. I’m waiting for Apple to mention something in release notes or Michael Tsai to say more.

  16. Hello,

    When I updated to Catalina, I started having problems with Apple Mail on my MacBook Pro.

    I’m now retired from the University of Illinois, but still use their email service. They utilize an Exchange server, and I started getting error messages for some of my incoming emails. The dialog error message box was:

    The message “[xxx]” could not be moved to the mailbox “Exchange”
    The specified object was not found in the store., The process failed to get the correct properties.

    The error needed to be cleared before any additional emails could be downloaded from the Exchange server, and sometimes there were quite a few of them. None of the messages showed up anywhere after clicking “OK”, either in Mail, or if I opened my email in Outlook on Safari. Fortunately, they were all messages I didn’t care about, and I think they all were targeted for deletion by my Mail filters. (I have at least a couple hundred filters.)

    After a back and forth with IT at the University, they pointed me to a possible solution at this website:

    Yesterday I went through the process of removing and rebuilding the Library files related to Mail as per the first fix described on that website. Quite a slow process for me, probably because my local Apple Mail folders go back to 1997. After some reboots and repeated rebuilds of various mailboxes, things seem to now be working ok.

    Too soon for me to know if things are permanently fixed, but so far, so good. I should note, however, that all my filters were turned off in the process (but they still were there) and I’m gradually reinstituting them as the myriad of spam emails now flood in. I’m also taking the opportunity to unsubscribe from most of the mail lists that I had previously just automatically deleted through my filters.

  17. Interesting article, thanks! But the comments following it are extremely frightening!

  18. On my MacBook running Catalina, an IMAP account in Mail has become very problematic. Messages no longer indicate they’ve been read after I open and read them. If I mark a message as Read, it switches back to Unread immediately. If I delete a message, it vanishes for an instant, then pops back. If I mark it as Junk, pretty much the same thing.

    I’ve run utilities, deleted the account from the computer and recreated it. No change.

    The account is through GoDaddy and accounts from other services don’t exhibit the problem. But when I run Mail on other computers with older OS’s, it works as it should. So I’m inclined to think the issue is in Mail and Catalina.

    If I turn off wifi, all of those issues disappear but as soon as wifi is on again, deleted messages re-appear and so on. But is that a failure of Mail to properly interface with GoDaddy’s servers or is it an otherwise unreported issue with GoDaddy?

  19. So Mail in Catalina works correctly as long as you’re using Ethernet? That’s… freaky. I can’t come up with any way of explaining that behavior.

    Have you checked with GoDaddy support about this? If it were generally a problem with Mail and Catalina, I imagine they would have heard about it by now.

  20. Sorry if I wasn’t clear about turning off the wifi. I’m off line altogether at that point; no ethernet, no nothing.

    So it clearly relates to being able to talk to the mail server, but there’s a failure in that communication that seems to be exclusive to the computer running Catalina.

    I have been checking with GoDaddy and can’t find anything and they claim there’s no issue on their end.

  21. Can you get them to say if other people are having similar problems?

  22. James, does you MacBook exhibit the same behavior on multiple (unrelated) wifi networks? Do other Macs on the same wifi network work correctly?

  23. In Catalina, my Mail app displays most messages correctly, but some messages have content replaced by the question-mark-in-a-box character and others have parts of the content missing entirely. Some of these message errors occur in a corporate Gmail account that I read in Mail (and I can see those messages just fine at, but other messages occur in an IMAP account (through DreamHost, and these appear fine in the webmail client).

    Seriously frustrating. FWIW, I love InfoClick, and that’s displaying things funny, too.

  24. That normally indicates a font issue. I would start by using Font Book to Validate all your fonts and eliminate any duplicates it finds.

  25. Thanks! I actually tried that already, on someone else’s recommendation, but no luck.

  26. I need to buy a new MacBook Pro (which will have Catalina installed) and migrate my data to it, including a large amount of POP email in On My Mac.

    My current MBP is a 2017 model, running Mojave (10.14.6).

    What is the easiest way of making sure I don’t lose my email?

    If it’s on a backup clone, will I later be able to import it?

    Thank you,


  27. It’s likely to be OK, but if you wanted to be extra careful, you could archive it using EagleFiler or MailArchiver X or MailSteward or such an app. That way no matter what Mail did to it, you’d be fine.

    In your case, however, since it’s all POP, it should just be .mbox files on your backup, which means that bringing it back in again shouldn’t be terrible.

  28. It’s likely to be OK, but if you wanted to be extra careful, you could archive it using EagleFiler or MailArchiver X or MailSteward or such an app. That way no matter what Mail did to it, you’d be fine.

    I see now that 10.15.3 supposedly avoids the problem, but I couldn’t wait any longer and finally migrated to the new machine (running 10.15.2) last week.

    As it turned out, I did lose massive numbers of messages, but luckily I had taken your advice and archived everything in EagleFiler beforehand, which I highly recommend.

    (The advantage over importing from a backup is that message status is preserved, plus of course you offload inactive messages from Mail.)

    In many ways this was a blessing in disguise, since I had been wanting to create an archive for a long time and had just been putting it off.

  29. I’m sorry to hear that you lost email, of course, but glad my advice was spot on. And EagleFiler is a good solution there. And doubly appropriate that it worked for you given that the author, @mjtsai, has been the primary conduit for warnings about Mail in Catalina.

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