It's called dictionary attack spamming

It works on a principle developed during the Second World War to try and break the Enigma code. Whereupon you try every combination of letters and numbers in the hope that maybe one or two might hit a target.

In a dictionary attack the spammer just sends email to every address in a dictionary of commonly used email addresses. Actually two dictionaries are used. One is commonly used user names. The other is known domain names. So you might have dan, danny, daniel, etc. in one dictionary and aol, netscape, mindspring, etc. in the other. The system then matches the names to the domains and blasts the spam out.

Obviously hotmail, aol, yahoo will be high on a dictionary attackers list

Never respond to a spam to remove yourself from their list. This single action will do more to protect your account than anything else.

Of all the Things I've Iost, I miss my mind the most