Oded,
Couldn't resist it - had to satisfy my own curiosity, and dragged my old Windows PC out of the cupboard.
(OMG, it's so slow!)
Anyways . . .
First of all, you need an App Password (obtained in Fastmail, via Password & Security)
Fired up Gmail Notifier Pro, and configured it:
IMAP server = imap.fastmail.com
Port = 993
Connection Security = Implicit
SMTP server = smtp.fastmail.com
Port = 465
Connection Security = Implicit
Tested with my Fastmail account and works OK.
