The information in this article is no longer the way to programmatically interact with Fastmail. Please see our information about JMAP instead!

If you're a programmer, and interested in helping to create extra functionality for FastMail, have a look at our FastServices API. It's a SOAP API that lets you get information from and manipulate a FastMail account. At the moment it's the API is very basic, but we're looking to expand it and feedback is appreciated:

FastServices Wiki page
FastServices Forum
Suggestions for a service idea