Over the years, I have seen Gmail come to make up anywhere between 40-60%+ of most B2C marketers' subscriber lists.

Google's reporting application, Google Postmaster Tool, has become a pivotal tool for any B2C marketer and has no comparable peer in its class.

It enables email marketers to reliably monitor their spam rates, authentication success, and domain/IP reputation directly with the mailbox provider.

On top of all of this, it is completely free to use.

While Google's help doc provides the basics of how it works, they do not answer how you can interpret the data like a seasoned veteran. That's what I'm here to do today.

Below you will find the culmination of my 5 years of experience with this tool summarized into how-to's around:

How to include it in your weekly marketing review

How to investigate issues elevated in Google's Postmaster Tool

Bonus: Common oddities to be aware of