Perhaps the most worrying problems being reported by early adopters of macOS 10.15 Catalina are in Apple’s Mail app. Michael Tsai, author of the superb SpamSieve, EagleFiler and more, has warned that some users are suffering data loss as a result. He therefore urges users to be very cautious about upgrading for the moment, writing “My advice is to hold off on updating to Catalina for now.”
Compounding this is the advice being given by Apple Support, that mail lost on Catalina can’t be recovered from Time Machine backups made in Mojave. Michael has shown that isn’t true, provided that previous versions of the folders are selectively imported using Mail’s Import Mailboxes command in the File menu.
If you have already encountered problems in Mail following upgrade, his article is essential reading. If you’re still wondering whether it’s safe to upgrade yet, you’d best read it now to ponder his advice.