Exchange 2003 Failover based on multiple Smarthosts.

Posted on 2009-04-15
Last Modified: 2013-11-30
Hi guys,

We are planning to use multiple smarthosts for failover purpose, so if one is unavailable Exchange route the messages to other one.
Following is details our of messaging infrastructure:
a) Only one Exchange 2003 server, single bridgehead and routing group.
b) Smarthost - 1
c) Single SMTP connector on Exchange with 'cost' value 1.

What would be the best possible solution, so Exchange do  the automatic failover to smarthost?

If we use single SMTP connector with 2 smarthosts entries seperated by semicolon (;) would it do failover or load balancing?

Is there any difference in using Semicolon (;) or Comma (,) to seperate multiple smarthost on single SMTP connector?

Thanks in advance,


Question by:fsaiexpert
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LVL 65

Expert Comment

ID: 24151016
Exchange doesn't do failover on smart hosts. The most that you can is load balancing, where all servers are listed in the SMTP connector and Exchange will use them all. Obviously if one isn't available then it will use another one.


Author Comment

ID: 24155611
What options are open to us then to do failover with Exchange?
We currently have a smarthost configured on the Internet Mail Connector.
We thought we could add in another smarthost with a semi-colon identifying failover:

should 1 not be available it will route to 2 exclusively.
your advice would be appreciated
LVL 65

Expert Comment

ID: 24157041
That is the only option available to you, but it will be load balancing, not failover. Exchange will attempt to use both servers.
If the first server is not available then it should use the second, but that will not stop it from trying to use the first.

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Author Comment

ID: 24157412
Would I be correct in suggesting that this may alternatively work and provide redundancy:

[IP1],[IP2] = load balancing
[IP1],fqdn = HA

1 IP 1 fqdn in the connector [ip1],fqdn this will go to IP1 until there is a failure with it, then it will continue to send there until IP1 becomes available (and for a little while afterwards).
LVL 65

Expert Comment

ID: 24158243
The article that you have posted isn't clear whether it will provide HA or not, it just states that it doesn't load balance. It may well be that Exchange will just ignore the second FQDN host when the first is referenced by IP address.


Author Comment

ID: 24158661
Thanks Simon,

In your experience have you ever seen the confi guration via the SMTP Connector Smarthost

[IP1],fqdn = HA

working for redundancy with Exchange?
LVL 65

Accepted Solution

Mestha earned 500 total points
ID: 24160057
I haven't done that myself.
I have done two hosts before for load balancing, but that is all.

Something else that I have done before is where the load balancing isn't done by Exchange, but by something else and Exchange is just pointed at a single location.
Another option is round robin DNS, but again that isn't HA, but load balancing.


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