This article explains how to track down a SPAMming script or breached SMTP account if your server is sending SPAM.

Parallels have provided an article with a full explanation of how to track down a SPAMming script or breached SMTP account if your server is sending SPAM.

It's extremely important to take care of any SPAM issues immediately once you become aware of the problem.

You can view the mail queue on a Plesk Linux server by logging into SSH and typing:

/usr/local/psa/admin/sbin/mailqueuemng

To delete the mail queue type:

postsuper -d ALL

To track down the SPAMmer please see (section "Statistics and Reports"):

https://docs.plesk.com/en-US/onyx/administrator-guide/mail/protection-from-outbound-spam.71349/