They use something called Jellyfish for spam detection and it's been pretty impressive. A few false negatives but overall catches most of it. And you can use their webmail or any IMAP/POP3/SMTP client.
A bit slow but I don't think it's unreliable. If it is, that's scary because how would I know :)
Just moved a folder with 1037 emails and it has 1037 on NameCheap now. Seems like it moved them all! (And it didn't take too long. It's moving a bunch of subfolders now.)
I just use a random cheap domain, registered through Gandi. This includes a couple of 3 GB mailboxes each with unlimited aliases, which is quite adequate if you don't use your email as a file store (much).
I suppose the "right" way would be through something like Fastmail instead, but the simple arrangement above has worked fine thus far.