Hello together,

The Egde Sender reputation checks seems to be very powerful. Exchange checks the sending server via a proxy.

The part, Exchange communication to proxy, is pretty clear for me and easy to configure.

... But I cannot find information what services the proxy need to provide.

For the communication proxy to internet sending system, what ports the firewall need to open?

What is the communication flow? The edge contact the proxy via port 80. The proxy contact to the sending system on port 80 and test if can send a mail with port 25 back to the edge?

Thanks a lot for your help

Best regards

Thomas

Edge will forge an SMTP message to test the sender if it will accept e-mail for delivery (to itself / edge) using a variety of protocols. For that, it can use a configured proxy server (and port), outbound from the Edge perspective. Depending on your proxy server, it could for example use http connect to connect to (your) port 25 using a proxy server at port 80.

https://technet.microsoft.com/en-us/library/aa995997%28v=exchg.141%29.asp

Hi Michel,

thanks for your information, this fhelps to understand how the edge perform his checks.

... but, does your link works for you?

Thanks

Thomas

• Edited by Tom Langer 23 hours 43 minutes ago

Hi,

If your organization uses a proxy server to control access to the Internet, you need to define details about the proxy server so that sender reputation can work properly (in particular, open proxy detection and sender blocking). You use the ProxyServerName, ProxyServerPort and ProxyServerType parameters on the Set-SenderReputationConfig cmdlet to define your organization's proxy server so sender reputation can successfully connect to the Internet.

The following table lists the outbound ports that are required for sender reputation.
 
More details about "Manage sender reputation" and "Network ports for clients and mail flow in Exchange 2013", for your reference:
https://technet.microsoft.com/en-us/library/bb125186(v=exchg.150).aspx
https://technet.microsoft.com/en-us/library/bb331973(v=exchg.150).aspx#MailFlowEdge

Thanks