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Round Trip SMTP Monitor Settings

Knowledge Front’s round-trip SMTP (also known as Mailive!) is a round-trip email transaction. We send you a test message and you forward it back to us at We track the round trip time, record any errors, and alert you to problems or delays.

You will need to set up what is commonly known as an auto-forwarder or auto-responder. See Round Trip SMTP Monitor Setup Help for how to set up the response on several of the most popular email servers

Test System IP Addresses

Test messages are sent from the following IP Addresses




  • 2604:180:1:2da::bce8
  • 2600:3c00::f03c:91ff:fe26:654e

Configuration Options

Basic Options

A name that might be more easily read than an IP address or hostname. Primary Mail Server for example.
Test account:
The email address where the test emails will be sent. This account should then return messages to in order to complete the round trip test. See Also Round Trip SMTP Monitor Setup Help
Test message frequency:
How often test messages will be sent in minutes. The system may send messages more frequently when a response has not been received from the previous test. This is an attempt to ensure the round trip test is not actually working before triggering an alert.

Delivery method:

Direct to IP address or Hostname
The SMTP connection will be made directly to the given IP or hostname. No MX record look-up will be performed.
Use Primary MX Record
Connections will be made to the primary MX record returned from a DNS look-up. If there are multiple records with the same weight the tests will round-robin between the records
Use MX Lookup with failover
Using DNS tests will be delivered according to the weight of the MX records. If a TCP connection error (timeout) or other non-fatal SMTP error occurs the same test will try on the next weighted MX record. This closely mimics the behavior of a typical mail server delivery.
Time zone:
The time zone you wish the reports to be displayed for. If you do not see your time zone listed contact us and we can add it, no problem.
Use TLS:

The choice as to whether Transport Layer Security should be used to deliver the test. There are three options:

On:Delivery will always use TLS and record a failure if the STARTTLS command does not succeed or if the SMTP transmission fails to complete in any way.
Auto:When the SMTP session begins the system sends the EHLO command to the SMTP server being tested and the response includes the capabilities of the SMTP Server. If STARTTLS is in the response then the test will attempt to use TLS and record a failure if the session breaks or the delivery does not succeed. If there is no STARTTLS then delivery happens the old fashioned way, with no encryption
Off:When sending a test e-mail the system will never attempt to initiate TLS, even if advertised in the EHLO response of the receiving server.

Advanced Options

Custom Subject:
For every test message the text of Custom Subject will be inserted before the unique message identifier.
Custom Body:
In the body of each test message the text of Custom Body will be inserted before the standard body of each test message. It will appear as the first line of the body.


No attachment is included with the tests
Word (docx)
Attach a unique Microsoft Word document to each test message. This can help test content and virus filter to ensure they are working. The document itself will be different for every test as will the document name.
PDF Document
Creates and attaches a unique PDF document to each test message. Document name and contents will be different for each test.
Time To Live in seconds. If a test takes longer that the TTL to return then it will be marked as a failure in the system. Useful for creating an acceptable round-trip threshold.
If selected tests hostnames will be resolved using AAAA records (IPv6). If no AAAA records exist for the given hostname or MX record the test will fail.
Message format
Setting for sending messages as either text/plain or text/html. Messages are normally sent as text/plain, but text/html is sometimes needed to trigger certain appliances to apply additional scanning to the messages.
Use Client Certificate
Knowledge Front test systems will present a SSL certificate to the remote server when delivering test messages. The CA for all Knowledge Front certificates is DigiCert.