Question Undelivered Mail Returned to Sender

[CercamiFacile]

Hi everyone, for some days I have been receiving hundreds of these emails from the server, where there are 100 domains, but this message refers only to [email protected]
I have limited the outgoing mails of this domain to 20 and in a few hours it tries to send 2718 mails.
I have immunify360 and it does not detect viruses and malware but these emails keep arriving and there are attempts to send emails. How can I check what emails are trying to send?

Ver.	Plesk Obsidian v18.0.33_build1800210225.14 os_CentOS 7
OS	CentOS Linux 7.9.2009 (Core)

Thanks

 

[Kaspar]

Check your maillog at /usr/local/psa/var/log/maillog to see who is connecting to your server.

Did you change the passwords for the mailboxes of the domain?

 

[maria_imunify]

Hello,

Please, submit your a support request explaining the issue here - Submit a request – CloudLinux

Our Imunify Security support team will investigate it and get back to you, thank you!