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Trouble with Mail Relay

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Trouble with Mail Relay - 9.May2016 9:05:02 AM

HimeshGohil

Posts: 5
Joined: 4.Apr.2016
Status: offline

Hi, I've just upgraded to exchange 2013 and relay is working fine apart from one server.
I've created a receive connector and tested relay from other servers quite happily, one particular one won't relay. When testing from Telnet, I get 5.7.1 unable to relay.

The server has been listed in the relay rule. It sits in the DMZ behind a firewall. Checking the firewall logs, I see the traffic being passed through with the correct IP's listed. As a precaution, I've added the firewalls IP to the relay connector in case exchange sees the firewall as the sender.
I've tried turning on verbose logging but my failed attempts do not get logged.

Any tips on what else I can do do discover where this is failing would help

Thanks,
Himesh

Post #: 1

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RE: Trouble with Mail Relay - 10.May2016 4:27:13 AM

HimeshGohil

Posts: 5
Joined: 4.Apr.2016
Status: offline

A little update, I've connected the server directly to the internal LAN to bypass the firewall and the mail relay works fine.
So it's only when running through the firewall. Inspecting the packets and it all looks fine. with the correct source, destination and sources.
Any other thoughts on how to check logs etc would be appreciated

< Message edited by HimeshGohil -- 10.May2016 6:10:31 AM >

(in reply to HimeshGohil)

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RE: Trouble with Mail Relay - 11.May2016 5:39:08 AM

HimeshGohil

Posts: 5
Joined: 4.Apr.2016
Status: offline

I finally tracked this down to the firewall natting the connection so the Exch server thought he traffic was coming from the firewall and not the client

(in reply to HimeshGohil)

Post #: 3

RE: Trouble with Mail Relay - 22.May2016 11:56:27 AM

Lekhan

Posts: 18
Joined: 4.Feb.2014
Status: offline

Possible you have NAT in your network, and source IP can be replaced by some NAT IP.
You need enable verbose logging for your receive connectors, and check via telnet "hello thisisatest"
Then find this string in transport logs. You will discover your real ip address.

(in reply to HimeshGohil)

Post #: 4