I have two at the moment separate emails, one exclusively for private use, friends, family ect., and one I use when I sign up for things like Horse Forum, ect. Helps to eliminate the junk from my private e-mail. To prevent it from happening again, I'd tell your friends to put an actual subject in the title, Party Tonight, or Homework Help, for example instead of just "hey". No one I know ever puts "hey" in the title, so those that do I skip, and those without actual email addresses I delete or spam. With all the craigslist stuff, I get spam mail, and sometimes it looks like an actual e-mail address, email@example.com
or something, but often I get e-mail addresses that are just a bunch of numbers and or letters, which is a sure sign that I don't want to even bother with them. I would just keep a closer eye on things, and like everyone else said, don't click on links unless you KNOW that it was sent by a friend, and you were expecting it. I got one once where it said "hey found a video of you, click and see" or something like that, fortunately others had already warned me about it, but it wiped a couple of my friends computers. You just need to be uber careful in this day and age.