FrontEnd SMTP Send Connector Test

To manage outbound external SMTP traffic, a FrontEnd SMTP Send Connector can be configured. If email delivery to external domains or to the internet takes too long, it could be because of a processing bottleneck at the FET SMTP Send Connector. By periodically evaluating the efficacy of each FET Send Connector configured, probable connector overloads and potential delivery bottlenecks can be captured early and eliminated. The FrontEnd SMTP Send Connector test helps with this. This test keeps track of the load on each connector, measures the message processing ability of the connector, and pinpoints those connectors where processing is bottlenecked.

Target of the test : A Microsoft Exchange 2013/2016 server

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for every Frontend SMTP Send Connector on the CAS server

Configurable parameters for the test
  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. port – The port at which the host listens.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Average recipients per message:

Indicates the average number of recipients handled by this send connector.


Typically, the type and number of recipients determines how an FET connector operates.

  • For messages with a single mailbox recipient, the FET connector selects a Mailbox server in the target delivery group and gives preference to the Mailbox server based on the proximity of the AD site;
  • For messages with multiple mailbox recipients, the connector uses the first 20 recipients to select a Mailbox server in the closest delivery group, based on the proximity of the AD site.
  • If the message has no mailbox recipients, select a random Mailbox server in the local AD site.

A high value of this measure is therefore indicative of the average workload of the connector.

Outbound connections established rate:

Indicates the rate at which outbound connections were established by this connector to the external SMTP server.


A steady increase in this value is indicative of an increase in workload.

Data sent rate:

Indicates the rate at which data is sent by this connector.


A consistent drop in these values could indicate a bottleneck in message transmission.


Messages sent rate:

Indicates the number of messages sent by this connector every second.