Configure 2 smarthosts for outgoing mail

Using Exchange 2003 in SBS2003 R2. We've setup a router with dual-wan capability in a fail-over mode (if wan1 goes down, wan2 opens up). We've setup the 2 mx records to point to the 2 public addresses and can receive email fine on wan2 when wan1 goes down.

Our problem is with sending. Our Exchange is configured to send mail through ISP1 smarthost, say smtp.isp1.net. When wan1 goes down, outgoing mail will go through wan2, but ISP2 will refuse to relay mail that is going to smtp.isp1.net, which is normal.

So how do you setup Exchange to use smtp.isp2.net smarthost when the "regular" Smtp connector using smtp.isp1.net does not work ?

Thanks.







ndidomenicoAsked:
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Alan HardistyCo-OwnerCommented:
SMTP Connectors can only be chosen / configured based on the recipient domain.
If you have two connectors and one is configured for one ISP and the other for the 2nd ISP, then one route will take preference over the other or you will send some mail out via one and some via the other, based on the Cost of the route.
The only thing you can do is to manually change the cost of the route when the link goes down so make the failed ISP connector less attractive to Exchange but this will be a manual change unless you can write some code to detect link availablility and to change the Cost of the route as and when the links come up / go down.
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xfreddieCommented:
I think this link has a simular question, and an answer.

http://forums.msexchange.org/m_1800461197/mpage_1/key_/tm.htm#1800461197

Greetz,
Xfreddie
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xfreddieCommented:
And it has alanhardisty solution in it .. ;)
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Alan HardistyCo-OwnerCommented:
: )
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krishnasmtpport25Commented:
Hi,

When you have configured smarthost on the exchange server. what happens in Exchange servers tries to establish the connection with SMTP servers and delivers the email to that servers and you can define the cost associated to it.

Create 2 SMTP connector with Cost 1 and cost 10. Configure cost 1 for ISP1 and Cost 10 for ISP2. Always lower cost is presidence. If exchange server could not establish connection with smtp.isp1 then it will use next connector with cost 10 and deliver the email throught smtp.isp2

Below link on how to configure SMTP connector
http://www.msexchange.org/tutorials/Configuring-SMTP-Connector.html

Hope this clarifies. Please let me know

Regards,
Krishna
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Jamie McKillopIT ManagerCommented:
Hello,

There is another option. You could use a service call "DNS Made Easy" (http://www.dnsmadeeasy.com/). This service allows for automatic DNS failover when a line goes down. Under your current setup, you can receive mail fine but I assume you lose access to OWA, Outlook Anywhere and any other services you make available to the outside. This service would allow automatic failover of DNS records to your standyby IPs, so those services would remain available.

It could solve your outbound mail problems also. You could have a DNS record setup that would use a hostname on your domain but would use the IP of your smarthost. If your line goes down, you could have the IP on that DNS record change to the IP of the smarthost of the other ISP. You would enter that DNS name into Exchange to use as the smarthost. This would allow for automatic failover.

JJ
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ndidomenicoAuthor Commented:
Thanks all. alanhardisty's solution in the provided link mentions creating a 2nd connector to another bridgehead server. Does that mean another Exchange server ? If so, this will not work since I have only 1 exchange server (sbs2003) in my domain.
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ndidomenicoAuthor Commented:
If possible, I would like not to have to do a manual intervention (changing the smarthost name in Exchange) so that the switch happens automatically. If no other option is available, then this is what we will have to do, but I'd like to get around this limitation).

I realize that external access services such as OWA, Vpn, etc might not work when on Wan2, but this is acceptable. We rarely experience downtime on wan1, and when it happens, it is only for a couple hours. So all we need during this time is Internet access for the lan and sending/receiving email.

Would a mail relay service (dyndns) be an option ?
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Alan HardistyCo-OwnerCommented:
My comment did not include a link - xfreddie posted the link.
Simple answer is this is not possible with just one server.
Your only control of outbound connectors is configured via the recipient domain - that's it.
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kdagliCommented:
You can ADD two smarthost in one connector, separated by ; (semicolon)


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