Mail.app fix for Fastmail SMTP in Mavericks

I've been having intermittent issues with Fastmail's SMTP service in Mavericks, where Mail.app will sometimes repeatedly reject the correct password (and thus refuse to send mail).

The fix is to force it to use port 587 for SMTP (it claims it'll try 25, 465 and 587 by default, but this doesn't seem to be reliable):

Preferences -> Accounts -> Fastmail -> Account Information -> Outgoing Mail Server -> Edit SMTP Server List -> Advanced -> Use custom port: 587