I've been using fastmail for a few years now and their reliability has been great, prices reasonable, and their web client is fast and convenient.

But there is one thing I cannot figure out. I have my own domain, say me@mydomain.com. The host for mydomain.com really is just a mail reflection service which sends to me@fastmail.com. When I send an email from the fastmail web interface, my identity is me@fastmail.com, and I cannot figure out how to make it accept me@mydomain.com.

There is a help page on setting up identities, but it doesn't work for me. :-( Other than than I'm 100% happy with fastmail.