Will having different macOS affect Mail?

I am looking at getting the new MacBook Air that will have Catalina installed on it. I have heard that Catalina can affect Mail, but if I use my Apple mail account on the new system and it is IMAP, will it affects all my Mail, since it is being synced?

Do other people have different OS’s on their systems and have you noticed any problems?

All the serious issues with Mail and Catalina that I have run across involve the loss of messages stored “On my Mac”, so if you have any of these it would be a good idea to archived those messages on a separate backup before you migrate from old to new Mac. There are also rumors that this most serious issue with Mail has been addressed in macOS 10.15.4 to be released soon, most probably on Mar 24, and almost certainly will be installed on that new MacBook Air just announced.

Al Varnell’s comments match my experience with Mail and Catalina. So far, I have had to rescue only one instance of “On my Mac” mail which disappeared on upgrade from Mojave.
The biggest shock in Catalina Mail is the loss of control of the user interface. Apple knows better how you should view your mail and in “Classic View” has removed column selection and positioning along with user-set column widths. This has raised havoc with users more comfortable with tabular format than with ‘iPhone’ format.

What a bummer. Hopefully that will return in a future update.

“raised havoc” doesn’t come close to how I feel about what Apple did by taking away perfectly fine and working display settings from an application that I use all day. There are a lot of threads, posts, articles, blogs, etc… all basically saying the same thing, “wtf Apple”?

Why do you stick with Apple Mail when it has always been one of the worst email clients?

I used to use Eudora, then Yahoo mail online, but Thunderbird works best for me because I can adapt it for my needs and write/create my own filters. Guess Apple is pushing for you to use its servers? I don’t trust Apple servers either. Good luck. Find a better mail client.

I’ve been using Mail since it first came out. I have tried others - they don’t offer anything more than I need. I send hundreds of emails a day and I must have at least 100K emails on file that I’m able to call up at a moments notice.

I broadcast to clients through groups.io.

I’ve been a happy Mac client since 1984.

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Beauty is in the eye of the beholder. Apple Mail works better for me than any of the other email clients I’ve tried.

Maybe I’m wrong about this, but I’ve always thought both Thunderbird and Apple Mail are email clients, not servers. I get email via my ISP and manage it via Mail; Apple does not require, or even push, an iCloud Mail account to use Mail.

Do you have any proof that Apple Mail is any less secure, or less privacy focused, than other servers? I’ve been thinking about switching to iCloud Mail because I’m getting tired of dealing with spam from my provider account.

Let’s not get into a “what’s best” argument because it’s all personal preference. The point is merely that those who rely on Apple Mail need to consider as part of their decision that it seems to have bugs that could cause data loss in Catalina. That generates three options:

  • Don’t upgrade to Catalina, which is a fine choice for some amount of time, but won’t be true forever (such as when you get a new Mac).

  • Switch from Mail to another email client. There are tons of them, and they all offer different sets of pros and cons.

  • Use Mail in Catalina and risk running afoul of the bug. It doesn’t affect everyone, so everyone can decide for themselves how much they want to play Russian roulette.

Adam, assuming I’ll buy a 14" MBP when it’s released, that will force me to migrate to Catalina, and I choose your option 3, can we try to get around these bugs by manually importing saved mailboxes instead of relying on the Catalina’s MA for that?

My understanding so far has been that the bug is related to On My Mac mailboxes. If, while still on Mojave, I save all those to files, and then after using MA to go to Catalina see that the email count in some/all On My Mac folders isn’t right, could I then choose to nuke those and instead import from my saved files. Would that work? Any pitfalls with such an approach?

I’m very much interest in any and all responses on this subject, as I was thinking of doing exactly the same…when the time comes.


From anecdotal net research…the problem involves gmail which I don’t use. However…I just bought a MailArchiver X license and imported everything before I updated, and set it for a weekly archive import as well. Single license needed for my wife and according to the author.

Are we sure we’re talking about the same issue? Lately I’ve usually been hearing about On My Mac emails disappearing as the “Catalina mail issue”. You mention gmail though which is (pseudo-)IMAP. Those two are mutually exclusive, aren’t they?

Alas, no. See:


There may be issues with Gmail as the server, but at least some of the problems (as noted above in @mjtsai’s post) involve mail hosted on iCloud.

Thanks for the clarification, Adam. We’re at .4 now, what a mess.

Ah…had not seen grokked that before. I do have iCloud email but it gets redirected to my real email account.