Spammers frequently send messages to groups of recipients whose userids or names are close to each other in the alphabet. For example, suppose I am user SPQR. When I open a spam message (assuming it has managed to get through hermes filtering) I might see a message which looks as though it is addressed to SPQ1000 in the
This is because the message header in a mail client doesn't have to list all the recipients' addresses. So although it looks as if it isn't addressed to you personally that could be because you weren't the first person in the list or, more likely, your username was put in the Bcc: field.
You may find the following useful: What is junk mail and what can I do about it?