A Breakdown Of Google’s Postmaster

Awhile back, we asked our deliverability guru Brad Gurley to weigh in on Google’s new Gmail Postmaster Tools. He gave us a small teaser of what he thought, but now he’s returned to us with his full breakdown. Enjoy!

It’s been nearly 2 months since Google announced their Gmail Postmaster Tools, designed to help senders manage their Gmail reputation and performance. A lot has happened in the world since July 10th – Chipotle delivery, a new iPhone, and an entire NFL preseason, for example – so what have we learned about Gmail delivery from our time with these tools?

What Are The Postmaster Tools?


Nearly every email blogger has penned a post describing the Postmaster Tools and what they do, so we wanted to take a slightly different approach. We’ll be talking about some of the tools we and our clients have found most useful, as well as some conclusions based on data seen in these metrics. For the most part, these conclusions fall in line with what we and others in the industry have been saying about Gmail for some time, but seeing the data from the proverbial horse’s mouth helps to really drive a few points home.

Of the tools offered, we’ve found that our team and most clients see the most value from the Spam Rate, IP Reputation, Authentication, and Delivery Errors categories, so we’ll focus on those here.

The Domain Abides


One of the first things you notice when you set up Gmail Postmaster Tools is the requirement for a domain name. As the internet moves toward IPv6, Google has heavily invested in tracking domain reputation. This is in contrast to most other major mailbox providers, who have focused primarily on IP address with domain as an afterthought. By using domain reputation alongside IP reputation, Gmail can better identify spammers who send mail across many different IPs in an attempt to dilute their negative engagement metrics, a tactic known as “snowshoeing.” This means that, especially to Google, the reputation of the sending domain is just as important as the IP address. Just like a famous area rug belonging to our cinematic hero The Dude, the domain really ties the whole thing together.



Let’s look at some metrics for a sample sender. Here you’ll see a domain with a very low spam rate, consistently less than 0.1%. Everyone knows that having a low complaint rate equals inbox delivery, right?


Not exactly. For this particular domain, we still saw some errors causing mail not to be delivered, so we had to dig a bit deeper.

We know that if a sender’s mail is primarily being delivered to the spam folder, the spam rate is almost always low, because users won’t be marking messages as spam if they’re already in the spam folder. However, we were able to eliminate that as the primary factor using seed test data and internal testing, so something else had to be in play.


By clicking on the dot for a specific date in the Delivery Errors page, we were able to see the specific reasons for the errors that had taken place that day. For this example, we saw that the reputation of the sending IP was the cause for nearly all of the errors that took place. Again, we see that even though the spam rate for the domain was very low, the reputation of the IP address(es) could be problematic.


The Postmaster Tools also provide a way to see the IP reputation, by viewing the aptly-named IP Reputation metrics. We can see that there are some IPs sending traffic for this domain that are marked with a Bad reputation at Gmail. By clicking on the blue area in the graph, we can pinpoint the problem IP addresses that correspond to that reputation level.

What Does It All Mean?


The Postmaster Tools are a great step forward in understanding your Gmail reputation, but they can’t do all the work for you. For example, once you’ve narrowed down which IP addresses have a Bad reputation, you’ll have to figure out why they are considered bad. Is traffic from other domains being sent over those IPs? Are the IPs brand new, and were they warmed up properly? Are recipients opening your emails? As Gmail’s Sri Somanchi said in 2014, there are hundreds of factors that determine whether your mail is delivered to the spam folder or the inbox. You can’t focus solely on engagement, or IP reputation, or domain reputation – your email deliverability must be viewed holistically to see the best results.


Brad Gurley is WhatCounts’ Director of Deliverability and a very handsome man. Check out his blog Delivery Counts, as well as other posts he’s done such as Gmail Deliverability Improvements: Tips And Tricks and Deliverability 101: Back To The Basics Q & A.

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