> It would also be nice if you could disable spam filtering entirely and run your own client-side.

It's horribly convoluted but it /is/ possible to do so:

http://webapps.stackexchange.com/questions/69442/how-to-disa...

I've been running it this way for about 18 months now after having a few important emails get gobbled up by their spam filter.

It's as if they intentionally want to force their filter on you. Not that there's anything wrong with a server-side spam filter. One that puts a polite X-Spam-Score header so you can adjust the sensitivity client-side.

Looking at the contents of my spam folder, and knowing that they likely reject many more e-mails in the background, I'm pretty sure I'd drown if I ever tried to use such option...