How does that work for IMAP access? Do you have an "application-specific password" like Google does, or just your regular password?

It doesn't exactly work like gmail does.

You can set many alternative login passwords in fastmail and the google auth is one of those.

So with the google auth you use your google auth fastmail password and append your google auth login so if your password is Password1, when you login you would be typing something like Password1123456 to login.

You can also set other login passwords for applications or imap with or without delete capabilities but a lot of the time they need full permissions to work with email clients, it could be nicer.

I believe pop/imap/smtp require "full access" type "regular" passwords.

I didn't see that. thanks