PSA: Apple Mail Bugs Can Lead to Data Loss in macOS Catalina

Michael Tsai, the developer of EagleFiler and the SpamSieve plug-in for Apple Mail on Mac, has written a blog post warning macOS users about potential data loss in Mail when upgrading to macOS Catalina 10.15.0 (build 19A583).

According to Tsai, he's heard from several users that updating Mail's data store from Mojave to Catalina sometimes says that it has succeeded, when in fact on closer inspection it turns out that large numbers of messages are incomplete or missing entirely.

In addition, users have reported the loss of message content when moving emails between mailboxes. From Tsai's post:
Moving messages between mailboxes, both via drag-and-drop and AppleScript, can result in a blank message (only headers) on the Mac. If the message was moved to a server mailbox, other devices see the message as deleted. And eventually this syncs back to the first Mac, where the message disappears as well.
Tsai warns that these issues are particularly pernicious because users may not realize anything's wrong unless they look at affected messages or mailboxes. Since the data is synced to the server, these problems can also propagate to other computers and devices, and relying on backups is difficult because Mail data is continually changing and there's no easy way to merge restored data with messages received since the last backup.

Despite the latter risk, it's still good practice to make backups, but Tsai notes that Apple Support appears to be erroneously advising users that lost Mail data in Catalina can't be recovered from a Time Machine backup made using macOS Mojave.

According to Tsai, this is not the case: Apple Mail's File -> Import Mailboxes... menu bar option can be used to selectively import them into Mail in Catalina as new local mailboxes.

Tsai says he's unsure whether these issues are due to Mail bugs or to other factors such as problems on the Mac or with the mail server. Apple released ‌macOS Catalina‌ 10.15.1 beta to developers on Friday, but it's still unclear if this version resolves the Mail app bugs. Regardless, Tsai's advice to users who rely on Apple Mail is to "hold off on updating to Catalina for now."

Affected readers can find the full breakdown of the issues here. Have you had problems with Mail since updating to Catalina? Let us know in the comments below.

Related Roundup: macOS Catalina
Tag: Mail

Top Rated Comments

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6 weeks ago
Looks like Apple has their own windows Vista.
Rating: 74 Votes
6 weeks ago


Who is heading the Mail department? I want him fired.

Newman is the head of the mail department.
Rating: 61 Votes
6 weeks ago
macOS Catalina is one OS to skip. Never read about so many bugs and other problems with a release of a fresh new macOS.
Rating: 53 Votes
6 weeks ago
Can all the people defending Apple like "it's ok to brick your system it's only beta" now wake up and see Apple has a software development problem that is getting worse and worse
Rating: 50 Votes
6 weeks ago
Good thing Apple had a beta to iron these critical bugs out!
oh wait...
Rating: 44 Votes
6 weeks ago
One would think a trillion dollar company could afford a QA department with people that are actually competent.
Rating: 39 Votes
6 weeks ago
Problems with iOS mail and now Mac mail. Dang.
Rating: 33 Votes
6 weeks ago
Waiting for our resident “Keep it up Tim, you’re doing a great job!” lapdogs to chime in defending this garbage. Apple’s QC, especially with regard to OS releases has become atrocious. Sure they release updates, but these problems should not be happening in the first place. Heads should be rolling over these shoddy releases.

But never mind bugs causing data loss. The stock is up and that’s all that matters right?
Rating: 32 Votes
6 weeks ago
macOS is the only thing keeping me buying the overpriced, poor quality e-waste junk that Macs have become. They have already messed up the hardware, but if they mess up the OS, there will be no point whatsoever.
Rating: 32 Votes
6 weeks ago


Can all the people defending Apple like "it's ok to brick your system it's only beta" now wake up and see Apple has a software development problem that is getting worse and worse


none of them wake up, mostly apple fed trolls.
it’s fascinating how our economy works today, Apple on an all time high. Products are near an all time low.
just overpaid junk and e waste.
Rating: 26 Votes

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