No, we are not infected. We just cannot be infected by mydoom because we run generally linux and you are on linux and to the top we don't read mail on teh server
We just hit by large amount of bogus traffic created by this virus. Obviously your email was in smb's addressbook whoase PC was infected with mydoom and mydoom started to send mails here and there using your email in From: field. That's why you get bounces.
Below is how virus is distributed.
QUOTE
In its movement through the Internet, Mydoom works like a standard e-mail virus: A Windows PC user activates the virus by opening its message's virus- laden attachment, and the virus sends itself out to the addresses it finds in the PC's address book. It also tries to spread by copying itself into any shared directories in the PC that are used by the KaZaA peer-to-peer file sharing network.