For Questions about Spam:

This is the very first thing on our signup page:

---- FastMail's systems track resource abuse and automatically disable relevant accounts. Things we keep track of include but are not limited to; the number of emails sent and received, amount of bandwidth used by sending and receiving emails, number and size of emails retrieved from external POP servers, number of signups, number of logins, etc. You should not sign up if you plan to use FastMail for sending or receiving hundreds of messages per hour, such as for spamming.

---- This is what happens when this is ignored: http://www.fastmail.fm/docs/faqparts/General.html#Locked

This is what we tell people who get fooled by forged headers: http://www.fastmail.fm/docs/faqparts/General.html#Spam

This is our SpamAssassin protection: http://www.fastmail.fm/docs/faqparts/Preferences.html#PrefSpam

This is how our Bounce feature works: http://www.fastmail.fm/docs/faqparts/Mailbox.html#MbxBounce

We keep a log of spammers who try to use FastMail.FM: http://www.fastmail.fm/docs/spam.html

Let me know if you'd like any further information.

Regards, Jeremy