SMTP Connector - queued mail between FE/BE

David Sutter · Joined: 05 Aug 2007 Posts: 3

I have a medium sized organization with several back-end Exchange servers
and two front-end servers used as SMTP gateways. The routing groups are
setup geographically with two sites being hubs, all the others being
connected to the hubs. In each of the hubs is one of the SMTP gateways.
The back-end servers route mail to each other using routing group
connectors, and all the sites use one of the two gateways for outbound
email. At some point two weeks ago (after Exchange SP2 upgrades and all
Windows 2003 updates) mail began queuing on the back-end server in one of
the hubs. One of the other server admins smarthosted the mail from it to
the remaining SMTP gateway. Now, the other servers were updated, and the
back-end server in the remaining hub is queueing mail in the same manner.

The queue is in the SMTP connector (on the back end server, not the
front-end), and shows the SMTP connector name followed by what looks like a
guid. The mail is stuck there with an error of "Cannot bind to the
destination server in DNS", but we use AD-DNS and all servers are able to
locate each other. If I smarthost the mail from the back-end server to the
front-end server, mail flows properly.

Archived from group: microsoft>public>exchange2000>transport

Leif Pedersen [MVP] · Joined: 05 Aug 2007 Posts: 193

Hi,

Try to run the winroute program (can be found on the exchange cd) and see if
the output tells you anything.

Leif

"David Sutter" wrote in message @TK2MSFTNGP05.phx.gbl...
>I have a medium sized organization with several back-end Exchange servers
>and two front-end servers used as SMTP gateways. The routing groups are
>setup geographically with two sites being hubs, all the others being
>connected to the hubs. In each of the hubs is one of the SMTP gateways.
>The back-end servers route mail to each other using routing group
>connectors, and all the sites use one of the two gateways for outbound
>email. At some point two weeks ago (after Exchange SP2 upgrades and all
>Windows 2003 updates) mail began queuing on the back-end server in one of
>the hubs. One of the other server admins smarthosted the mail from it to
>the remaining SMTP gateway. Now, the other servers were updated, and the
>back-end server in the remaining hub is queueing mail in the same manner.
>
> The queue is in the SMTP connector (on the back end server, not the
> front-end), and shows the SMTP connector name followed by what looks like
> a guid. The mail is stuck there with an error of "Cannot bind to the
> destination server in DNS", but we use AD-DNS and all servers are able to
> locate each other. If I smarthost the mail from the back-end server to
> the front-end server, mail flows properly.
>

David Sutter · Joined: 05 Aug 2007 Posts: 3

All of the connectors involved in outbound mail appear to be working (one
unrelated one isn't). The only thing that I've identified is that the
Virtual Server FQDN was changed from the server name to
mx1.ExternalDomainName.com (what it is aliased as externally). Could this
cause a problem when the Back End server tries to send mail to it (after
correctly identifying it in DNS)?

Also, unrelated, I see a section called "Routing groups not found in Active
Directory". Where do they come from and is it worth my time to adsiedit and
delete them?

"Leif Pedersen [MVP]" wrote in message
news:%23HzIugIjGHA.5036@TK2MSFTNGP04.phx.gbl...
> Try to run the winroute program (can be found on the exchange cd) and see
> if the output tells you anything.

Leif Pedersen [MVP] · Joined: 05 Aug 2007 Posts: 193

Hi,

I have seen a problem at one client site where they changed the SMTP FQDN to
the same name as their external name and mail internally stopped because the
internal server in another routing group were not able to resolve the
external name to an internal IP address. We fixed the problem at that site
by adding the MX1 record tho their DNS (fortunately they used a split brain
DNS).

Leif

"David Sutter" wrote in message @TK2MSFTNGP05.phx.gbl...
> All of the connectors involved in outbound mail appear to be working (one
> unrelated one isn't). The only thing that I've identified is that the
> Virtual Server FQDN was changed from the server name to
> mx1.ExternalDomainName.com (what it is aliased as externally). Could this
> cause a problem when the Back End server tries to send mail to it (after
> correctly identifying it in DNS)?
>
> Also, unrelated, I see a section called "Routing groups not found in
> Active Directory". Where do they come from and is it worth my time to
> adsiedit and delete them?
>
> "Leif Pedersen [MVP]" wrote in message
> news:%23HzIugIjGHA.5036@TK2MSFTNGP04.phx.gbl...
>> Try to run the winroute program (can be found on the exchange cd) and see
>> if the output tells you anything.
>
>

David Sutter · Joined: 05 Aug 2007 Posts: 3

This was the problem and solution for me. After adding in the records in
DNS mail works perfectly. No restart of any services required.

"Leif Pedersen [MVP]" wrote in message @TK2MSFTNGP05.phx.gbl...
> Hi,
>
> I have seen a problem at one client site where they changed the SMTP FQDN
> to the same name as their external name and mail internally stopped
> because the internal server in another routing group were not able to
> resolve the external name to an internal IP address. We fixed the problem
> at that site by adding the MX1 record tho their DNS (fortunately they used
> a split brain DNS).
>
> Leif

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