Fastmail Auto-Configure Chooses Wrong Port for Thunderbird

I thought I’d post this minor discovery here in the hopes that others would find it useful. I love Mozilla’s Thunderbird email client. It does everything I want it to, including PGP/GPG via Enigmail, Calendering via Lightning, and Google contacts and Tasks via the Provider for Google Calendar extension.

But I just couldn’t get it to get all my folders to sync on Mint GNU/Linux. Only the top level INBOX would download when connecting with my IMAP provider, Fastmail

Turns out a “smart” engineer at Fastmail changed the auto-configure IMAP SSL port from 993 to 992 to get Thunderbird to work better with some non-compliant email programs, including Microsoft’s Outlook and Apple’s Mail. I had tried every possible solution including subscribing to specific folders and renaming the root folder until I found this post:

Alternate Namespace in IMAP

It’s a clever hack that makes Fastmail work better for Apple, Windows, and Blackberry users but it confuses the heck out of compliant client users who allow Fastmail to auto-configure settings.

Changing SSL port 992 to 993 fixes the problem.

It’s okay to use the autoconfig – it works fine otherwise – but if you’re not getting all your mail try switching ports. 993 is standard, 992 is a hack for non-compliant clients (which, apparently, is pretty much everybody).