Perhaps it depends with what services you use it? 
Personally I&#x27;ve only ever used it with Apple&#x27;s iCloud&#x27;s mail service which worked great but didn&#x27;t support custom domains. I also used it as a POP client for Gmail (mostly because Google&#x27;s IMAP support initially was horrible and their tags didn&#x27;t play well with IMAP folders back then).
I can say though that FastMail&#x27;s IMAP service works flawlessly for me, and so does the mail.app client for it.<p>Yes, Airmail is still supported, but IMHO its UI suffers from severe feature creep. I also found it never reliably notified me that account passwords needed to be changed. I used it against MS Outlook, and whenever the password on the backend needed to be changed after 60 days, Airmail would simply sit there and not receive any new emails.