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Exchange 2003 Standard SMTP connectors

fosseitsl asked
Medium Priority
Last Modified: 2012-05-06
I have a single default SMTP connector that sends all outbound emails to a smarthost.  My boss wants a second connector setup so that if the smarthost is unavailable the emails will send through DNS lookups.  is it a case of just creating another Virtual SMTP connector and how to setup the failover.  (simple solution please)
A secondary part of this is that we might have an external server that will want to relay through on this redundant connector.  No issue with setting up a relay exception rule through a Default Virtual SMTP Server - but do I get the emails from an external ip address to use the newly discussed redundant Virtual SMTP connector?
With Kind Regards
Paul Holoway
May not be able to respond to questions until Monday!
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tigermattSite Reliability Engineer
Most Valuable Expert 2011


To have a backup Send Connector, create the Send Connector as usual and set it up with how you want email to be sent through it: http://www.amset.info/exchange/smtp-connector.asp.

Then, to configure this as a 'backup' connector, go to the 'Address Space' tab on it and Edit the default '*' address space. The cost value is what determines which connector is used with first, second, third... priority. Set the cost value to any value HIGHER than the cost on the '*' address space on your main connector. This is normally 1, so set the Cost on the backup connector to 2 and be done with it.

Expert of the Quarter 2009
Expert of the Year 2009

I actually don't think that will work. It will depend what the response is when the smart host is down. SMTP Connectors don't do failover very well, then can load balance, but that is about it.



Thankyou for your responses
Mestha - are you refering to tigermatt's response?
What about trying to get the external server to relay to a different smtp connector?
Expert of the Quarter 2009
Expert of the Year 2009
Yes, I was referring to the earlier response.
There is no failover in SMTP connectors. I think if the connector with cost 1 fails, then it will not try connector of cost 2. You would need to have both connectors with a cost of 1.


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Thankyou Mestha,
Further investigation into the issue - I have created a second SMTP Virtual Server with inbound port of 2525 and set the relay through this port and limited to the ipaddress of the external server thus leaving the Default SMTP Virtual Server to deal with normal inbound email.

Please state whether it is possible to redirect the second SMTP Virtual Server to a specific SMTP connector?
Expert of the Quarter 2009
Expert of the Year 2009

It is not possible to force the SMTP connector to use a specific SMTP virtual server.
All the SMTP connector does is ask the OS for SMTP, it could be on one or the other of the SMTP VS.

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