HOW TO: Configure the SMTP Virtual Server for Message Delivery

After a connection has been opened and the receiving server has acknowledged that it is ready to receive data, messages can be transmitted for delivery. This step-by-step article describes how to deliver messages.

Configure Retry Tries and Intervals

If a message cannot be delivered on the first try, the Microsoft Simple Mail Transport Protocol (SMTP) Service sends it again from the Queue directory after a specified time. You can set the interval between delivery tries and also designate the number of times to try to deliver a message. After the limit is reached, the non-delivery report (NDR) and messages are sent to the Badmail directory.

You can use these settings to increase your server output speed, but these settings affect outgoing messages only and have no effect on the rate at which other servers process incoming messages. To configure these settings, follow these steps:

1. In the Microsoft Management Console (MMC), click to select the SMTP virtual server, and then click Properties on the Action menu.
2. Click the Delivery tab.
3. For First retry interval (minutes), type a value for the time to try delivery before posting the first notification. The default is 15 minutes.
4. For Second retry interval (minutes), type a value for the time to try delivery before posting the second notification. The default is 30 minutes, which is 30 minutes after the first retry interval.
5. For Third retry interval (minutes), type a value for the time to try delivery before posting the third notification. The default is 60 minutes, which is 60 minutes after the second retry interval.
6. For Subsequent retry interval (minutes), type a value for the time to try delivery before posting a notification. The default is 240 minutes.

Set the Message Hop Count

When a message is delivered, it may be routed to a number of servers before it reaches its final destination. You can designate how many servers the message is permitted to pass through. This is named the hop count. To set the message hop count, follow these steps:

1. In the MMC, click to select the SMTP virtual server, and then click Properties on the Action menu.
2. On the Delivery tab, click Advanced to open the Advanced Delivery dialog box.
3. For Maximum hop count, type a value for the number of hops a message can take between the source and destination servers. The default is 15 hops.

NOTE: After the hop count is set, the SMTP server counts the hops that are listed in the Received fields of the message header. When the number of Received fields exceeds the maximum hop count setting, the message is returned to the sender with an NDR.

Set the Masquerade Domain

The masquerade domain replaces any local domain name that is used in any Mail From lines in the protocol. The replacement occurs on the first hop only.

1. In the MMC, click to select the SMTP virtual server, and then click Properties on the Action menu.
2. On the Delivery tab, click Advanced to open the Advanced Delivery dialog box.
3. For Masquerade domain, type a domain name that you want to appear in message headers, instead of the actual name of the domain.

NOTE: All replies to such messages are routed through the SMTP virtual server that uses the masquerade domain.

Set a Fully Qualified Domain Name

At startup, the name that is designated on the Network Identification tab of the System Properties dialog box is automatically used for the fully qualified domain name (FQDN). If you change the name (either manually or by joining a Microsoft Windows 2000 domain), the new name is automatically used for the FQDN the next time the computer is restarted. You do not have to perform any action to update the FQDN for the virtual server.

To override the automatic use of the computer and domain names on the Network Identification tab, change the FQDN in the Advanced Delivery dialog box (this is accessed through the Delivery tab). The Microsoft SMTP Service can then use the designated name instead of the name that is specified on the Network Identification tab. To set the FQDN, follow these steps:

1. In the MMC, click to select the SMTP virtual server, and then click Properties on the Action menu.
2. On the Delivery tab, click Advanced to open the Advanced Delivery dialog box.
3. For Fully-qualified domain name, type the FQDN.

Configure a Smart Host

You can route all outgoing messages for remote domains through a smart host instead of sending them directly to the domain. This permits you to route messages over a connection that may be more direct or less costly than other routes. The smart host is similar to the route domain option for remote domains. The difference is that after a smart host is designated, all outgoing messages are routed to that server. With a route domain, only messages for the remote domain are routed to a specific server.

If you set up a smart host, you can still designate a different route for a remote domain. The route domain setting overrides the smart host setting. To set up a smart host, follow these steps:

1. In the MMC, click to select the SMTP virtual server, and then click Properties on the Action menu.
2. On the Delivery tab, click Advanced to open the Advanced Delivery dialog box.
3. In Smart host, type the name of the smart host server. You can type a string to represent a name, or you can type an IP address.
4. If you want the Microsoft SMTP Service to try to deliver remote messages directly before it forwards them to the smart host server, click to select the Attempt direct delivery before sending to smart host check box. The default is to send all remote messages to the smart host, not to try direct delivery.

NOTE: You can identify the smart host by the FQDN or by an IP address. Note that if you change the IP address, you must also change it on every virtual server. If you use an IP address, enclose it in brackets ([]) to increase system performance. Microsoft SMTP Service checks first for a server name, then an IP address. The brackets identify the value as an IP address, so the DNS lookup is bypassed.

Enable a Reverse DNS Lookup

If you select this option, Microsoft SMTP Service tries to verify that the IP address of the client matches the host or domain that is submitted by the client in the EHLO or HELO command.

NOTE: Because this feature verifies addresses for all incoming messages, its use can affect Microsoft SMTP Service performance. Clear the check box to disable the feature.

If the reverse DNS lookup is successful, the Received header remains intact. If the verification is unsuccessful, "unverified" appears after the IP address in the Received header of the message. To enable reverse DNS lookup, follow these steps:

1. In the MMC, click to select the SMTP virtual server, and then click Properties on the Action menu.
2. On the Delivery tab, click Advanced to open the Advanced Delivery dialog box.
3. Click to select the Perform reverse DNS lookup on incoming messages check box.