- One or more users of your domain are receiving unwanted mail from an external user id.
- Option 1: Blacklist the id from sending mail to any user on your domain
Refer to the steps mentioned here to blacklist the sender's email id. After blacklisting the domain, no users from the blacklisted domain will be able to send any mail to any user on your domain.
- Option 2: Ask the user on your domain to blacklist the sender from the Quarantine report received to them through email