I've been using them since January 2008 and I couldn't be more pleased. Their documentation is excellent (e.g. https://www.fastmail.fm/help/features_plus_addre

I've been using them since January 2008 and I couldn't be more pleased. Their documentation is excellent (e.g. https://www.fastmail.fm/help/features_plus_addressing_and_subdomain_addressing.html https://www.fastmail.fm/help/features_plus_addressing_and_su...) and their blog often has cool little technical details about how they solved certain problems (e.g. http://blog.fastmail.fm/2012/11/26/inter-tab-communication-using-local-storage/ http://blog.fastmail.fm/2012/11/26/inter-tab-communication-u...)