Fastmail.fm
fastmail.fm, without a doubt. I've been with them more than a year now and is absolutely superb.
Two things:
- look at their blog and the clarity and completness of information presented about system status. Is't clear that they care about realiable email and it shows.
- the web interface is fantastic! So good in fact that I'm think of dropping my super-sophisticated imap client for it.
There is a reward program but I won't be so cheap to ask you put my email as you subscribe.