Downgraded from Catalina to Mojave and can't open newer mail

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Downgraded from Catalina to Mojave and can't open newer mail

Recently decided to downgrade from Catalina to Mojave due to issues with the built in CAC support. Previously was using Pkard CAC enabling S/W but it is not longer supported in Catalina. Dues to many issues with the built in support decided to roll back. Rolled back via Time Machine to which worked great. Then restored my more recent mail (~library/mail) . When opening mail, I now get an error: Mail Library cannot be read because its format requires a new version OS. Upgrade you Mac to a newer version of MacOS to use mail.

Well, can't do that. Is there a way to have the Mojave version of mail open the Catalina version of the mail files?

iMac 21.5", macOS 10.13

Posted on Oct 31, 2019 5:43 PM

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Answer 1

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frogdog1 Author

Level 1

14 points

Nov 4, 2019 6:01 PM in response to Barney-15E

Turn out it wasn't so bad. I was able to restore to my last Mojave mail then import the mbox files from my catalina backup. It took a while, but was pretty painless. Just a little bit of clean up was necessary.

Thanks

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Answer 2

Barney-15E

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116,740 points

Oct 31, 2019 6:37 PM in response to frogdog1

You can't restore a newer version of the Mail library.

You need to restore the version that existed with Mojave.

You can back up your Mail folder, then possibly import the raw message files from that after you restore the Mojave version.

The messages are stored in ~/Library/Mail/V7/

The subfolders will have a unique ID as the name.

You can dig into those, then the mbox folders, and further in until you find elmx files. You can QuickLook them to see what they are. Easiest would be to order by date and look at the ones after your Mojave backup.

Any emails on an IMAP or other network server will be updated automatically and you shouldn't need to have to import them.

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Answer 3

frogdog1 Author

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Nov 1, 2019 8:50 AM in response to Barney-15E

I figured that was the case but thought I might get lucky with an easier solution. Unfortunately restoring to my mojave backup would lose three weeks of mail. I was hoping to get catalina working with CAC support but couldn't and finally gave up. It's locally stored email that I'm trying to recover. Thanks!

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Answer 4

Barney-15E

Level 10

116,740 points

Nov 1, 2019 6:11 PM in response to frogdog1

Unfortunately restoring to my mojave backup would lose three weeks of mail.

That's what I was explaining how to restore. It's not simple, but it can be done.

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Downgraded from Catalina to Mojave and can't open newer mail

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