Transport SMTP Receive Connector Test

Exchange 2013/2016 servers running the Transport service require Receive connectors to receive messages from the Internet, from email clients, and from other email servers. If a mailbox user complains that he/she is unable to receive certain messages or is receiving messages slowly, very often the source of such problems would be the receive connectors. Administrators should hence be able to figure out instantly which receive connector could probably be contributing to this problem condition and why – could it be because the receive connector is getting choked owing to an overload? Or is the connector  rejecting too many messages owing to a size limit violation? The Transport SMTP Receive Connector test provides accurate answers to these questions. This test auto-discovers the SMTP Receive Connectors and for each connector reports the load on that connector and the number of messages rejected by that connector. This way, the test points to connectors that are overloaded and those that are rejecting too many messages.

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

Agent deploying the test : An internal agent

Outputs of the test : One set of results for each Transport SMTP receive connector

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

Data received rate:

Indicates the rate at which data was received by this connector. 


A high value over a period is indicative of an excessive use of the SMTP server. Under such circumstances, compare the value of this measure across receive connectors to know which connector is contributing to the heavy load on the SMTP server.

Inbound connections to the receive connector:

Indicates the number of inbound connections to this receive connector.


The value of this measure indicates the connection load imposed by the send connectors of the Front End Transport service and the Transport service on the same Exhange 2013/2016 server, and the Transport and Mailbox Transport services on external Mailbox servers. In the event of a connection overload, you may want to compare the value of this measure across receive connectors, to know to which receive connector the send connectors are connecting often. 

Messages received by receive connector:

Indicates the rate at which messages are received by this receive connector.


Compare the value of this measure across receive connectors to know which receive connector is receiving a steady flow of messages. In the event of an overload, this measure will lead you to the exact connector that could be experiencing the overload.

Messages rejected due to size restriction:

Indicates the number of messages rejected by this connector because of a size restriction.


If the message quota of a receive connector is set too low, then you will have too many messages to the connector getting rejected. To avoid this, you may want to reconfigure the message size quota of the connector with the highest rejection quotient. To identify the connector, compare the value of this measure across receive connectors.