Forwarding eMails from Exchange to Icewarp bounces back, but not via distribution list

Question

we are testing heavily Icvewarp as replacement for our outdated Exchange.

Unfortunatly there is nearly no docu around in the internet, which makes it not easy 🙁

We have now set up the Icewarp together with the Exchange.

All mails coming to the Exchange postboxes are forwarded via a user-setting to the Icewarp server.

Icewarp server uses Exchange as mail-relay.

Therefore all incoming eMails should get received by both servers and all sending is done via Exchange.

But unfortunatly this only happens with half of the mails.

If someone send a eMail from outside or inside to a distribution list on the Exchange server, the eMail is received by all members of that distribution group in Exchange AND in Icewarp. Which is fine and as expected.

BUT if someone send a eMail to a Exchange user, the Icewarp server blocks the message creating a error-message in Exchange AND Icewarp saying:

Diagnoseinformationen für Administratoren:

Generierender Server: exchange.mydom.ccom

[email protected]
icewarp.mydom.com #501 5.7.1 <[email protected]>... Permission denied ##rfc822;[email protected]

Ursprüngliche Nachrichtenköpfe:

Resent-From: <[email protected]>
Received: from "some server on the Internet"

Environment:

Exchange with domaine Mydom.com and DNS exchange.mydom.com
Icewarp with domaine Mydom.com and DNS icewarp.mydom.com.
In Exchange for every user a additional mail-contact pointing to the eMail-address [email protected]
In Exchange a forwarding for every user to his mail-contact pointing at [email protected]
Exchange configured as mail-relay for icewarp.
Icewarp configured to use Exchange as mail-realy.
MX-record mydom.com pointing to exchange.mydom.com
MX-record icewarp.mydom.com pointing to icewarp.mydom.com
In Icewarp, Exchange is listed as "Trusted Host"

We need to solve this problem urgently as our testing is stopped and more and more colleauges began supporting sticking on Exchange, which i really don’t like to 🙁

Thanks for any help.

email bounces exchange mail forwarding smtp

Ivan_Wang · Answer

Try to run the following command to trace the forward emails(Message Tracking Log), maybe it could help you find the reason why the SMTP sender missed:

Get-MessageTrackingLog -Sender <Sender's email address> -Recipients <Email address from icewarp server> -MessageSubject "<Subject>" -Start "<Start Date and Time>" -End "<End Date and Time>

Chris9834 · Answer

thanks for your answer.

Question 1: Yeap, the Sender does not show up in the eMail, see picture.

This is true no matter where the sender ist. But when sending a eMail to a Exchange-Distribution group (like those Fail2Ban Messages) it shows up. My Exchange Account ([email protected]) is configured to forward eMail to a Exchange Mail-contact which points to [email protected]

In the FROM field of the Mail-Source you see:

From: - - <[email protected]>
To: myuser <[email protected]>

and in the smtp-log you see:

109.233.XXX.XXX [00007F713A59E700] 13:52:04 <<< EHLO exchange.mydom.com
109.233.XXX.XXX [00007F713A59E700] 13:52:04 >>> 250-icewarp.mydom.com Hello exchange.mydom.com [109.233.XXX.XXX], pleased to meet you.
109.233.XXX.XXX [00007F713A59E700] 13:52:04 <<< MAIL FROM:<> SIZE=4130 BODY=7BIT
109.233.XXX.XXX [00007F713A59E700] 13:52:04 >>> 250 2.1.0 <>... Sender ok
109.233.XXX.XXX [00007F713A59E700] 13:52:04 <<< RCPT TO:<[email protected]> NOTIFY=NEVER
109.233.XXX.XXX [00007F713A59E700] 13:52:04 >>> 250 2.1.5 <[email protected]>... Recipient ok
109.233.XXX.XXX [00007F713A59E700] 13:52:04 <<< DATA

When doing the forwarding i tried all ways i could think of.

transport rule to mail-contact -> permission dienied
postbox fording to mail-contact -> permission denied
transport-rule to mailing list -> permission denied
postbox forwarding to mailing-list -> OK, but sender is missing

HINT: i think the problem is because BOTH eMail-servers are configured to the SAME eMail-domaine mydom.com but have different hostnames, IPs and DNS but the same ´domain part (exchange.mydom.com and icewarp.mydom.com both for eMail mydom.com) I#, sure that's the base reason for that trouble as internal Spam & Abuse prevention rules try to block it.

Ivan_Wang · Answer

I'm here to confirm your current trouble: Did the emails which were sent to the distribution group that includes one mail-contact member(myuser@icewarp.domain.com) not show the SMTP sender email address on icewarp server?
If so, could you get the SMTP email address if you send emails from another domain email address to this distribution group? Could you see the SMTP send email address by view the From entry in the message header?
To make all incoming emails of Exchange Server copied to icewarp server, you could also create a transport rule(If the recipient is located inside the organization, Cc/Bcc the message to a specific email address from icewarp server).

Forwarding eMails from Exchange to Icewarp bounces back, but not via distribution list

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