I believe the real issue here is its not uncommon for spam services to try to locate valid email addresses. Generally, an email server won't accept email to an

I believe the real issue here is its not uncommon for spam services to try to locate valid email addresses. Generally, an email server won't accept email to an invalid users and will probably start flagging the incoming server/domain as those attempts start to cross a threshold of some sort. OP is talking about *@example.com as a catchall which means a spammers script will sit there and email a dictionary of usernames against your domain until it crosses it's own threshold. It's not too hard to add an alias for each name as you go along but it really depends whose list your domain gets on.