import accounts blank

I'm having the same problem. Currently using macOS 11.6 on a MacBook Pro, an iMac, and a late 2013 Mac Pro, and I get the same behavior on all three systems. I've tried installing the latest public release of MailMate, and also the special build for Big Sur.

With every macOS update, Apple makes some change to how Apple Mail saves its accounts. There's no official API to access this information and it was probably a bit naive of me to try to work around it :)

I'm eventually going to remove the importer completely (it still works on older macOS releases). I'm working on a “wizard” that should, hopefully, be able to get most things right based on just email addresses, but this isn't fully implemented yet. Until then “File > Add IMAP Account” is the only option, but often it's also sufficient to enter the email address in this window if it's, e.g., a @gmail.com address.

I'll update this ticket in case of progress on the “wizard”.