That is outgoing spam. You will need to find out and prevent this asap to prevent your server from getting blacklisted.
You will need to start looking at your mail log to identify and who are sending the emails.
It may be a compromised account or a spoofed email.
You need to stop this at the earliest, else you are risking the genuinity of valid emails as well, and a good chance that the IP address will be blacklisted and treats all your emails from the server as spams. Check through the email logs and find the culprit.
Kevin Cheri : Senior Server Administrator / Freelancer : 9+ years Exp, reach me out for any help Server Optimization Expert / Mysql Guru / Migration Specialist
Skype : lynxmaestro
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