Alerts not working just for one user? maybe its spam...

Hey, I was just reminded in the msd2d.com discussion groups about an issue I had with a customer about a two years ago. They had one user who never got alerts. All the other users got the alerts with no problems, but this one user got nothing. He was able to sign to the alert, when checked in the database you saw that he was signed to the alert, but when the list would change - other user got the email and he didn't! I will spare you the whole story (took us a month to chase it down). It turned out the outlook 2003 was treating sharepoint emails as just mail. Why? I cant tell. Perhaps the user was annoyed by a different alert, set junk on it and forgot about it... Hope your users are more careful!