The OJS System is sending spam

Hello, I have a problem that involves ojs system. I searched the forum but have not found something similar.
A system user (chief editor) contacted saying that the email account it is sending spam. He has several accounts in the OJS system, but only a user who has an e-mail of our specific domain is sending spam. When ojs system is offline, sending spam by email from our server stop being sent.
Is there any possibility of being sent spam by the OJS system?
Thank you very much!

This is probably an indication of a virus/bot/worm infection of your server. This could happen by unpatched vulnerabilities at the system level, or by insecure file permissions at the OJS level.

Try running an antivirus scan on your install to see if you can find any infected files.