Options not usable when PMG is not the first receiving MX?

[itNGO]

Question: When PMG has another Mailgateway in front of it, which is receiving the Mails as defined per DNS mx, are there options which can not be used anymore in PMG?

For example, enabling SPF still possible?
What about DNSBL?
I am asking, cause the first MX has the far better already paid AV-Scanners but not so good E-Mail-Security. Or do we have to "rotate" this and PMG is the first HOP and forwards to the far better AB-Scanner then?

 

[dietmar]

Question: When PMG has another Mailgateway in front of it, which is receiving the Mails as defined per DNS mx, are there options which can not be used anymore in PMG?

There is not network info, and no bad (client) behavior detectable. Only static mail content can be analyzed, so detection rates will be quite bad.

 

[dietmar]

Or do we have to "rotate" this and PMG is the first HOP and forwards to the far better AB-Scanner then?

Yes, this setup is far better.