SMTP Connectors are the mechanism Exchange 2010 uses to transfer mail between the Exchange infrastructure and external systems using the SMTP protocol. These external systems can include other email domains on the Internet, smart hosts such as mail filtering appliances, your ISP’s smart host, your SharePoint farm, etc. They are found on Exchange servers running the Hub Transport and Edge Transport servers, and there are two kinds: Inbound SMTP connectors are for accepting email from other systems using the SMTP protocol.

1. Outbound SMTP connectors are for sending email to other systems using the SMTP.

Exchange 2010 supports three other kinds of connectors. Foreign connectors use drop folders (local or network share) to store messages other applications can pick up for processing. Linked connectors are pairs of Inbound and Outbound connectors to maintain a relationship with a system like your anti-spam, archiving, or data loss prevention system, and Routing Group connectors are for transferring mail between Exchange 2010 and your legacy Exchange systems.

When you use EdgeSync to subscribe your Edge Transport servers to your Hub Transport servers, the necessary Send and Receive connectors are set up automatically to provide for incoming and outbound mail flow. However, you may want to create other connectors to deal with different systems, to provide fault tolerant paths for email to traverse between your Exchange system and the Internet, or if you are not using the Edge Transport server role and want to configure your Hub Transport server to directly exchange email with Internet systems, or some other system in your DMZ.

Configuring SMTP Send Connectors

You can use either the Exchange Management Console, or the Exchange Management Shell to create an SMTP Send Connector. The EMS may be the cleaner way to go, but there are so many options that the EMC will make this much easier. There are four types of Send Connector:

1.  Custom connectors connect with systems that aren’t servers running Exchange 2010.
2. Internal Send connectors send e-mail to servers in your Exchange organization. This connector is configured to route e-mail to your internal Exchange servers as smart hosts.
3. Internet Send connectors send e-mail to the Internet. This connector is configured to use Domain Name System (DNS) MX records to route e-mail.
4. Partner Send connectors send e-mail to partner domains. This connector is configured to only allow connections to servers that authenticate with Transport Layer Security (TLS) certificates for SMTP domains included in the list of domain-secured domains. You can add domains to this list by using the TLSSendDomainSecureList parameter in the Set-TransportConfig command.

To create a Send Connector, follow these steps:

1. Log onto the Exchange 2010 Hub Transport server.
2. Launch the EMC.
3. Navigate to Organization Configuration, Hub Transport.
4. In the Action pane, click New Send Connector… to launch the wizard.
5. The wizard prompts you to give the connector a name, and to select the intended use. When naming a connector, use a descriptive name, and consider creating a name without spaces like SMTPtoSharePointFarm. This will make it easier to use PowerShell later to work with the connector.
6. Select the use for the new connector and click Next.
7. Specify the address space to which the connector will route mail. Specify the domain name you wish to use and whether or not to include subdomains. You can use ‘*’ to indicate all domains. Then specify the cost. The cost is important if there is more than one connector that can be used, where the lower the cost the more preferred the route. This is useful if you have two Internet connections, and only want to use the slower one when the faster is down. Like weights in SRV records, the values are arbitrary. 1 vs 10 is no different than 1 vs 2, as long as there are no others you want to squeeze between them.
8. If you wish to limit the systems that can use this Send Connector, select the option to make it a Scoped send connector.  When done, click Next.
9. You can either use DNS to route mail directly to an MTA, or select to route mail through a smart host, like your Data Loss Prevention or content-screening system, or your ISP’s SMTP relay. Click Next.
10. Add any additional Hub Transport servers you want to share this connector, and click Next.
11. Click New to create the connector.

 Now that you have created a new Send Connector, you may wish to modify its properties. To do so:

1. Select it in the lower panel, right-click it, and choose Properties.
2. In addition to making changes to your choices made when creating the connector, you can set protocol logging levels and the maximum message size. Both of these settings are on the General tab.

Configuring SMTP Receive Connectors

Like the SMTP Send Connectors, you can use either the EMC or the EMS to create SMTP Receive Connectors. Again, the EMC is probably the better choice. There are five possible use types for Receive Connectors:

1. Client Receive connectors receive e-mail from users of Microsoft Exchange. This connector is configured to only accept client submissions from authenticated Microsoft Exchange users. The Client usage type is only available for Receive connectors configured on Hub Transport servers.
2. Custom Receive connectors connect with systems that don’t include servers running Exchange.
3. Internet Receive connectors receive e-mail from servers on the Internet. This connector is configured to accept connections from anonymous users.
4. Internal Receive connectors are used to receive e-mail from servers within your Exchange organization. This connector is configured to only accept connections from Exchange servers.
5. Partner Receive connectors are used to receive e-mail from partner domains. This connector is configured to receive mail from domains included in the list of secure receive domains. You can add domains to this list by using the TLSReceiveDomainSecureList parameter in the Set-TransportConfig command. Mutually authenticated TLS connections are required for domains that are on this list.

To create a new Send Connector, follow these steps:

1. Log onto the Exchange 2010 Hub Transport server.
2. Launch the EMC.
3. Navigate to Server Configuration, Hub Transport, and in the upper pane, select the server you wish to configure.
4. In the lower pane you will see any Receive Connectors that were automatically setup by the EdgeSync process or manually created.
5. In the Action Pane, click New Receive Connector.
6. The wizard prompts you to give the connector a name, and to select the intended use. When naming a connector, use a descriptive name, and consider creating a name without spaces like SMTPfromSharePointFarm. This will make it easier to use PowerShell later to work with the connector.
7. Select the use for the new connector and click Next.
8. If you have multiple IP addresses assigned to the server, select the IP address to which you wish the connector to bind.
9. Enter the FQDN that the server will use to identify itself to HELO and EHLO messages. Click Next.
10. By default the connector will accept connections from any IP address that can reach it. If you wish to narrow the field, enter the appropriate IP address or subnets, then click Next and Finish to create the connector.

Once created, you will want to configure your connector. Follow these steps to configure the Send Connector:

1. Right-click it in the lower pane and choose Properties.
2. You can set the protocol logging level on the General tab, and also set a maximum message size for inbound mail. You can also make changes to the settings you used to create the connector in the General and Network Tabs, but if you made the desired choices, move on to the Authentication Tab.
3. Here you can set the requirements for Authentication, including whether or not to use TLS, Basic, etc.
4. On the Permission Groups tab, you can specify who can submit mail to this Receive Connector.
5. Click OK when done.

When moving mail between systems that are not in the same Exchange infrastructure, like other systems on the Internet, your internal SharePoint or ERP systems, or to act as a relay for printer/scanners or alerts, you can configure SMTP connectors. Just remember that you need an Inbound connector to receive email, and an Outbound connector to send mail, and you will be all set.

Article By: Eva Ciganova (90 Posts)