Error 554 5.4.6 Hop count exceeded - possible mail loop

Question

_{Friday, November 23, 2018 9:59 AM}

Hello,

I have an Exchange Server 2013 and i want to configure it to send mail through my antispam. I have configured a custom send connector and then returns the error that i have mentioned in the title. I'll try to explain how i have the system:

Reception process: "internet --> firewall --> antispam in dmz --> exchange server"

Send process: "exchange server --> firewall --> internet"

All correct. With this setup is working.

Now i want to send mail through the antispam:

Reception procress: idem

Send process: "exchange server --> antispam in dmz --> firewall --> internet"

I have set a custom send connector redirecting mail to my antispam and the antispam relay outside. In receive connector i have not set anything because mail is already receiving through the antispam.With this setup i get the error: 554 5.4.6 Hop count exceeded - possible mail loop

If i connect directly to the antispam and do a send test, it sends correctly. I think that the problem is in the connectors.

Someone can help me?

Thanks and regards

All replies (7)

_{Saturday, November 24, 2018 11:54 PM}

It's hard to say since you didn't tell us the configuration of the send connector and your environment.

Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
Celebrating 20 years of providing Exchange peer support!

_{Monday, November 26, 2018 6:45 AM}

Hi paresant,

Which kind of antispam do you use?

How do you configure send connector on your Exchange server and this antispam server?

As the error message says, make sure there doesn't exist a loop between them, make sure this scene doesn't occur: send connector on your Exchange server sends mail to your antispam server, then your antispam server sends mails back to your Exchange server.

Regards,

Kyle Xu

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_{Tuesday, November 27, 2018 1:05 PM}

Sorry, i have updated my question with my enviroment configuration. I used symbol "-->" within "" and didn't appear the explanation of my enviroment configuration.

_{Tuesday, November 27, 2018 1:07 PM}

Thanks for reply. My antispam is: Anti-Spam SMTP Proxy (ASSP) Server.

Configuration of send connector:

Type: custom

Route mail through smart hosts: antispam ip

Uncheck use external DNS

Address space: *

Cost: 2

source server: my exchange server

Uncheck scoped send connector

The antispam is setup to receive from exchange server and relay to internet.

_{Tuesday, November 27, 2018 1:53 PM}

Toolbox log:

Identity: exchangeserver \ Submission \ 59257663783009
Subject: relay assp test
Internet message ID: "<[email protected]>"
From the address: [email protected]
Status: Retry
Size (KB): 18
Message origin name: SMTP: Default EXCHANGESERVER
IP of origin: 192.168.64.65 (antispam ip)
SCL: 0
Date received: 11/27/2018 14:28:48
Expiry time: 11/29/2018 14:28:48
Last error: A local loop was detected.
Queue identifier: exchangeserver \ Submission
Recipients: [email protected]; 2; 0; [{LRT =}; {LED =}; {FQDN =}; {IP =}]; 0 ;; 0

_{Tuesday, November 27, 2018 6:26 PM}

We can't see all the settings of the non-Exchange parts, but the NDR would suggest that one of the hops is sending outbound mail back in.

Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
Celebrating 20 years of providing Exchange peer support!

_{Sunday, December 2, 2018 8:53 AM}

Hi paresant,

To narrow down this issue, you can bypass the antispam server you used(Send emails to the internet by send connector). If this issue doesn't occur, it means this issue is caused by a wrong setting on your antispam server.

If you still cannot send emails to the internet, you can use the command below to check mail flow on your Exchange server:

Get-MessageTrackingLog -Sender "[email protected]" -Recipients "[email protected]" -MessageSubject "xx"