The SMTP Connector on Exchange is a powerful tool for an Exchange administrator. It allows you to make SMTP email work in the way that you want it to, instead of allowing Exchange to try and work it out for you.
An SMTP Connector plays no part in the delivery of email to mailboxes hosted on your Exchange server. Even in the "inbound" scenarios outlined above, the connector is being used to send the email to another server.
SMTP connectors are not server specific. They are stored in the AD domain as part of the Exchange org. Therefore when you are moving to a new server or introducing additional servers you will not need to create additional connections, simply adjust the existing ones.
If you are co-existing with Exchange 2007, then an SMTP Connector will be seen by Exchange 2007 as a Send Connector that it cannot modify.
It is now becoming quite common for some of the large ISPs such as AOL and many others to tighten the configuration of their email servers in an attempt to reduce the spam being sent. This has caused problems for many operators of Exchange servers as email from their servers are being rejected as well.
If you are on DSL, or any kind of dynamic IP address, then you may be caught in this trap.
For advice on what AOL are now looking for, take a look at this page from AOL: http://postmaster.info.aol.com/trouble/
If you are unable to fulfil AOL's or the other ISPs requirements, or need a solution quickly, then you can setup an SMTP connector on your Exchange server which will allow you to route email through your ISPs SMTP server. This server will pass AOL's tests and should work for any others that you are having problems with.
For relaying to another server (internal or external)
Remember that if you want your server to relay for a different domain to a different server then you need to configure a different connector for each server.
If you have multiple connectors, especially a connector that has a * in the address space (for sending email via your ISP) then you need to adjust the cost carefully. The wildcard SMTP connector with the * should have the highest cost, SMTP Connectors pointing to internal servers should have the lowest (so that they are used first). If you want to load balance the connectors then you can set multiple connectors at a cost of 1.
Q: I don't see Admin and Routing Groups
A: The display of Admin and Routing groups isn't enabled as default. You need to enable it by hand.
Right click on your organisation name right at the top of ESM and choose Properties. Enable both boxes. Apply/OK and you should see the extra options.
Q: What happens if I don't take the * out of "Address Space".
A: All of your email is sent out via the ISP email server. While this isn't a problem, some people prefer to send most of their email direct.
Q: How can I find my ISPs Smart Host?
A: Look on their web site for their outbound SMTP server. Another good trick is to look for their instructions for Outlook Express. This will usually have their SMTP server listed. Otherwise you may have to call them to find out what it is. While you are on the phone, check whether you need to authenticate when sending only. Don't use the term smart host though, as it only confuses them.
Q: My ISP requires authentication to use their SMTP server
A: You need to add a username and password to the SMTP configuration. On the properties of the connector click on the "Advanced" tab. Click on the "Outbound Security" button. Change from anonymous to basic authentication. Click on the "Modify" button and enter the username and password as required.
Q: Why not specify the smart host in the SMTP virtual server?
A: While this option would work if you wanted to send all email out through the ISP email server it can cause problems. The key issue is if you have more than one Exchange server. Configuring a smart host on the SMTP virtual server breaks replication between the servers.
Q: I already have a connector to send email through our front-end server/spam server.
A: If you are using a third party server then you will need to look at the configuration to see how to direct email to another machine.
If you already have a connector to route email through a front-end server then add the new connector as indicated above, but only add the Front-End server in "Local Bridgeheads".
Q: Is this an alternative to getting reverse DNS configured?
A: No - you should still get your ISP to make a reverse DNS entry for you if possible. This is good practise for a machine connected to the Internet. We have more information on configuring your DNS here.
Q: How can I use a connector to bypass my ISPs block on SMTP traffic and use a third party SMTP Server? I don't see where I can set the port.
A: If you need to use an alternative port for SMTP traffic, then adjust the SMTP virtual server first. Another option would be to create another SMTP virtual server, on the same IP address as your main server. Then change its port. Once set, change the SMTP virtual server being used as the bridgehead in the SMTP Connector. By using an additional SMTP virtual server you can leave the default on port 25, which is good for use with additional Exchange servers.
Q: Can I use more than one SMTP Connector with the wildcard?
A: If you have access to two SMTP servers that you can relay email through then you could add both on separate SMTP connectors. Both SMTP connectors would need to have the cost set as 1 and the address space as *. However you could also set both smart hosts on the same connector separated by a semi-colon (as indicated above).
Q: Can I have a fail over configuration, so the second connector is only used if the first is not available?
A: No, this is not possible. If you have two connectors, both with the address space set as * and the cost as 1 and then 2, Exchange will ignore the connector with a cost of 2. The most you can do is load balance, with the same cost of 1 on both connectors.
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