I am getting a lot of "Undelivered Mail Returned to Sender" messages for mail I haven't sent from an "alias" email address of mine.
I am receiving a lot of "Undelivered Mail Returned to Sender" messages in an "alias" email account on sbcglobal.net my wife uses for mail we have not knowingly sent. Most of it now ends up in the Spam folder but I am concerned that the email account is compromised.
This happened
Every time Firefox opened
== A couple of months ago.
Opaite Mbohovái (1)
This is not really a Firefox problem :)
It's possible there's no problem, since unfortunately spammers send spam pretending to be from regular people's e-mail addresses (you don't have to have the access to the person's e-mail account for that).
It's also possible that the account and/or PC is indeed compromised. You could change the account's password and run a virus scan just in case.