suspicious email

Hello all, I am new here and have not really used forums before and I have not had issues with Norton so I do not go through the site and I am old school so if there is not a problem I generally don't go trying to find one.  "if it aint broke don't fix it".  anyway every once in awhile I get notification of undeliverable emails and the addresses are unknown and today was even in Italian.  I do not understand what is going on but suspect that my computer is infected with perhaps roboware or something similar.  It does not majorly affect my computer but there are small things that seem strange.  Is there a fix for this?