A few months ago I tried out Runbox.com with a trial account. While I haven't signed up at this point, I was very impressed by the features of the account. If I ever decide to pay for an email account, Runbox would be one of the first companies I would consider.
So what was great about Runbox? It was fast, easy to use, stable and seemed a great email service. I would reccomend signing up for the trial account
dan