Good news, your computer is clean of any viral infection. Great! :)
You can't be "attacked" by mailer deamon as it never run on your computer.
mailer deamon is a service that run on every server. It's purpose is to transmit e-mails to the correct address. When it's asked to deliver an e-mail to an non-existing address, it generate a message that is sent to the sender to inform him of the problem.
Now, everybody should know that spammers always use fake sender information. When a SPAM message is sent to a non-exitant address, BUT with a valid sender or reply adrress, and that it appens to be yours, you receive those error notifications.
In your case, it means that your e-mail address have been somewho harvested and abused from virus infected computers used to relay SPAM e-mails.
It can be harvested from social sites like Facebook, compromised sites, infected computer, posts on various forums,...
Nothing you can do now, sory :(
Electro, February 2012
