Within the last few days, one of our users has been sending outgoing emails to bogus email accounts. The result has been over 6000 emails bouncing back. This isnt very friendly as im sure my server has been blacklisted.
Does anyone know how to stop this? emails are sent from nobody@<myhostname.com>. I didnt know who it was at first, but after reading the attachment, i see that each mail has this at the bottom:
Mail sent from WebMail service at <website name>
At first i thought the customer was sending out spams intentially, but he denies that. Could this be a virus or trojan on his computer?
It's strange that the emails are being sent from nobody@<hostname.com> but his website name appears at the bottom of each email.
Is there any prevention against users sending spam through the SMTP server and also to prevent the bouncebacks?
I'm in desperate need of help, as 6000+ emails is a pain and my customer is clueless as to what has happened.
Your help is greatly appreciated!