Send connectors

Applies to: Exchange Server 2013

In Microsoft Exchange Server 2013, a Send connector controls the flow of outbound messages to the receiving server. Send connectors are configured in the Transport service on Mailbox servers. Most commonly, you configure a Send connector to send outbound email messages to the Internet through a smart host or using DNS routing.

The Transport service on Exchange 2013 Mailbox servers requires Send connectors to deliver messages to the next hop on the way to their destination. Send connectors are stored in Active Directory and are available to the Transport service on all Mailbox servers in the organization.


When you deploy Exchange 2013, outbound mail flow cannot occur until you configure a Send connector to route outbound mail to the Internet. For more information, see Create a Send connector for email sent to the Internet.

Selecting the Type for a Send connector

Typically you create a Send connector in the Mail flow section of the Exchange admin center (EAC). When you create a new Send connector, you choose an available Type appropriate to your connection scenario. The type determines the default permission sets that are assigned on the connector and grants those permissions to trusted security principals. Security principals include users, computers, and security groups.

Procedures that explain specific Type selections include Create a Send connector to route outbound email through a smart host and Create a Send connector to send email to a partner, with Transport Layer Security (TLS) applied.

In you prefer using the Exchange Management Shell to the EAC, you can create a Send connector and specify a type by using the New-SendConnector cmdlet.

New Send connector features in Exchange 2013

The relationship between the Front End Transport service on Client Access servers and the Transport service on Mailbox servers introduces new behavior for Send connectors.

  • The FrontEndProxyEnabled parameter of the Set-SendConnector cmdlet is available to make a Send connector in the Transport service route outbound mail through the Front End transport service on a server in the local Active Directory site. This configuration consolidates how email is routed from the Transport service. For more information, see the following topics:

  • The IsCoexistenceConnector parameter has been deprecated. In most cases, we recommend the Hybrid Configuration Wizard to configure some of your mailboxes in on-premises Exchange and some in the cloud.

  • The LinkedReceiveConnector parameter has been deprecated. This parameter was used to create Send connectors that could route messages to a third-party anti-spam service. In most cases, you now route mail to your anti-spam service using your MX record, so the linked-connector behavior is no longer necessary.

  • The default maximum message size, specified by the MaxMessageSize parameter, has been increased from 10 MB to 25 MB. Set-SendConnector provides more information on how to set parameters on a Send connector.

  • The TlsCertificateName parameter has been added. Use this parameter to authenticate the local certificate that's used for outbound connections, and to minimize the risk of fraudulent certificates.