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Exchange 2010 - Not forwarding non exchange emails to MDaemon Smart Host

Posted on 2011-10-27
Medium Priority
Last Modified: 2012-05-12
Hi Guys,

I have got the following:
MX Record forwarding emails to my TMG 2010 box which then forwards mails to my EDGE server and my Edge server forwards to my CAS/HUB (Exchange 2010).

We have got a couple of users on MDaemon that is not in Exchange so Exchange should forward all emails to the smarthost if they don't exist on exchange.

Instead external users get the followin NDR:
The following message to <testmail@domain.com> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-'5.1.1 User unknown'

Final-Recipient: rfc822;testmail@domain.com
Action: failed
Status: 5.0.0 (permanent failure)
Remote-MTA: dns; [192.168.xx.xxx] (This is my TMG Server IP)
Diagnostic-Code: smtp; 5.1.0 - Unknown address error 550-'5.1.1 User unknown' (delivery attempts: 0)

I have created a Send Connector as follow:
FQDN = exchange.domain.com
Address Scope: Type = SMTP, Address = *, cost = 1
Network: My smart host IP xxx.xx.xxx.xx
Source Server: Both my cas servers CAS1 and CAS2

I have created the Accepted Domain and set it as an Internal Relay

When sending email from internal to one of the users on MDaemon, everything works fine. But external users sending mails internally receives the above NDR.

When looking at the live logs on TMG I get the following :
A non-SYN packet was dropped because it was sent by a source that does not have an established connection with the Forefront TMG computer

I have created an additional receive connector as follow:
FQDN = exchange.domain.com
Network: Use these local IP addresses to receive mail = (All Available IPv4) with ports: 25, 443, 80
Network: Receive mail from remote servers = internal and external IP of my TMG server
Authenticate: Nothing selected (I have also tried with other authentication types which did not help)
Permissions Group: Anonymous users, Exchange Servers, Partners all selected.

Any help would be appreciated.
Question by:Hendrik Wiese
  • 4
LVL 37

Accepted Solution

Jamie McKillop earned 2000 total points
ID: 37039818

You have recipient verification enabled of your Edge server. This does a lookup in AD for all recipient addresses. If it can't find the address, which would be the case if these mailboxes are on a foreign mail system, it will reject the message. You will need to turn off recipeint verification.


LVL 21

Author Comment

by:Hendrik Wiese
ID: 37043321
Hi jjmck,

Thanks for you comment, but it was already disabled (Please see image below). Any other suggestions would be greatly appreciated.

 Recipient Filtering Properties
LVL 21

Author Closing Comment

by:Hendrik Wiese
ID: 37043337
Hi jjmck,

Sorry the screenshot above refers to the filter on the edge server in stead of the hub.

Your Solution worked GREAT!!!

LVL 21

Author Comment

by:Hendrik Wiese
ID: 37043553
Sorry just a quick question, the users are now receiving the following although the mails are being delivered to the mailbox, do you know a quick fix?:

Delivery has failed to these recipients or distribution lists:
An error occurred while trying to deliver this message to the recipient's e-mail address. Microsoft Exchange will not try to redeliver this message for you. Please try resending this message, or provide the following diagnostic text to your system administrator.
The following organization rejected your message: domain.com.
LVL 21

Author Comment

by:Hendrik Wiese
ID: 37043705
Any ideas?

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