PRTG's Email Round Trip Sensor and Google Mail

Originally published on April 14, 2010 by Daniel Zobel
Last updated on March 03, 2022 • 4 minute read

Email round trip sensors ensure the end-to-end delivery of emails and make it possible to monitor availability and performance of a complete email delivery process. In order to test your own mail servers for delivery to external mail accounts, you need a third party mail account on the Internet. Our experience is that round trip monitoring works very well with Google Mail, as it operates reliably and there are virtually no downtimes on Google's side (which means practically no false alarms).

We have been using Google Mail for "email round trip monitoring" since last year. Below is a graph that shows the results between December 1, 2009 and March 20, 2010. Combined uptime of our mail server plus Googlemail was 100% (no downtime in 109 days).

Screenshot of our email monitoring

Our Configuration

We are using PRTG’s built-in Email Round Trip sensor to perform the following test every 15 minutes:

  • PRTG delivers an email for a dedicated Google Mail account into our mail server (MS Exchange)
  • The Exchange server delivers the email to Google Mail
  • The email account is set to auto-forwarding to a dedicated email address on our email domain
  • Optional: Google Mail delivers the email to MessageLabs (we use their Anti-Spam services)
  • Finally the email is delivered to our exchange server via SMTP
  • PRTG scans the dedicated mailbox using IMAP (or POP3) until the email arrives

The average delivery time for this process for the last 4 months was around 11 seconds.

Monitoring Multiple Aspects of Your Email Delivery

This test is great because it checks so many aspects:

  • Does my mail server accept emails that need to be relayed to the outside world?
  • Does my mail server actually deliver emails to the outside world?
  • Are MX records for my email domain set correctly?
  • Can email be delivered to my mail server?
  • Can my mail server receive emails?
  • Does my mail server process and forward incoming mails correctly?
  • Can users access their emails using POP/IMAP?
  • Does all this happen in a timely manner?
  • Are all necessary Internet connections working?

If any of these aspects was broken, an email round trip sensor would fail. Get your free trial version of PRTG  today and try for yourself!

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