The Simple Mail Transfer Protocol (SMTP) monitor verifies that the SMTP mail server can accept incoming sessions and respond in a timely manner.
To verify, the SMTP monitor uses the following process:
- Opens a connection to the specified SMTP mail server and waits for the server to respond with a standard Service Ready Code 220 opening message.
- When the monitor receives the opening message, the monitor safely disconnects from the server by sending a QUIT command to terminate the SMTP connection.
- If the mail server fails to respond or responds with an error code indicating that the service is not available, ipMonitor considers the test to have failed.
Use the SMTP Monitor to verify that:
- A mail client can open a connection with an SMTP mail server.
- The server adheres to the SMTP protocol by responding with the correct codes.
- The server responds within a required number of seconds.
Minimize the SMTP server load
SMTP servers are configured to perform a reverse lookup on all incoming connections. This process verifies that the IP address of the SMTP client matches the host or domain submitted when the connection is established.
Because the IP address of the SMTP Monitor can be verified each time the server is tested, delays can occur when connecting to the server, or the load on your SMTP server can increase if aggressive timing parameters are used.
To avoid this issue, you can:
- Add a reverse DNS entry for the ipMonitor host machine.
- Adjust the SMTP monitor's timing parameters by increasing the Maximum Test Duration value and the Delays Between Tests parameters.