In actuality, your email account is perfectly safe. What is happening is that a spammer is masquerading as you or an address within your own domain. There is little security in email; try going into the account settings in your email program. Where you type in your name and email address, put “Bill Gates” as your name, and “firstname.lastname@example.org” as your email address. Send a new message to your own (real) email address, and in a second, you will have what appears to be an email from Bill Gates of Microsoft. Not too hard to masquerade yourself, is it?
This is the technique employed by many spammers out there. Unfortunately, since they are sending the messages through mail servers other than our own, there is nothing we can do to block it. It usually lasts a few days, and then they move onto to the next victim. It’s unlikely that is personal, and until authentication and anti-spam technology improves, you basically just have to put up with it until it stops. If you notice that the bounce-back messages are going to a particular email address that you do not use (eg. email@example.com), let us know, and we can block any emails to that address.