Block incoming mail based on delivery hostname instead of IP

[xyptilon]

I'm using an anti-spam cluster and want to reject all e-mail, except if it comes from the anti-spam cluster.

However, their cluster is using many ip addresses from many ranges and blocking based on that is not really an option. They suggest only allowing their delivery hostname (https://my.spamexperts.com/kb/31/Accept-email-only-from-the-Hosted-Cloud-filter-nodes.html), though I'm not sure how to configure this in Plesk.

Does anybody have an idea?

I'm using Plesk 12.5.30 (Web Host edition for VPS) + CloudLinux support, Security Pack, Power Pack and have the commercial MagicSpam plug-in as well.

 

[IgorG]

I suppose that you can try to use instruction for Postfix from your reference.
Have you tried it?

 

[IgorG]

Also there is special addon - https://my.spamexperts.com/kb/469/Plesk-addon-for-Linux.html

 

[xyptilon]

Thank you for the prompt reply.

The server is using Qmail and I've tried the instructions, but that breaks authenticated SMTP functionality.

The plug-in is for the interface an single-sign-on to their control panel, it does not offer functionality to limit incoming connections to their cluster.