Hotmail accounts very frequently bounce messages due to their extremely small storage quota. I had been manually deleting these bounces for years now, but it is a bit annoying for me. From this day forward I will be unsubscribing hotmail accounts who bounce more than 3 times.
As an alternative mail service, please consider this free webmail service: http://www.fastmail.fm They are run by some BSD users in Australia, with a larger free quota, extra services like spamassassin, webmail and IMAP access. I don't know them personally, but their webpage seems to be brutally honest (to a point of saying known bugs and future plans) and a few of my friends are using them now. Warren