Google Postmaster Tools: Domain vs. IP address Data Thresholds

Today's guest post is from Brian Curry, Manager of Deliverability, for Merkle Inc.. Take it away, Brian!

Since July of 2015, Google rolled out a shiny new tool for the Deliverability community to poke around and nerd out. We all know Google hasn’t always been the most transparent to Senders, so while we play with our new Gmail toy, we start to notice small things that perhaps give us clues into Google’s mind.

Consensus has been that volume that needs to exceed about 500/day on an IP address to warrant Google displaying reputation data for that IP address. Domain Reputation seemed to follow the same criteria (as far as we knew). Until a smaller volume sender showed something different for Domain Reputation thresholds.

Filtering to show the last 120 days of data...

We see the data point move on the Domain Rep graph to 3/16 with a High Rep, but the IP graph does not budge…interesting. What the below graph suggests is Domains have a lower volume threshold to display data.

More details for this given scenario:

  • This Sender has a dedicated IP and Domain for their use only.
  • No spikes in other Postmaster Graphs during this timeframe.
  • 12/29 - only 95 Gmail users were sent 
  • 1/12 - we saw 5,400 Gmail users sent.
  • 3/16 - the day the Domain Rep graph shoots up, only 65 Gmail users were sent. 

Notice how the IP address does not have a data point on 12/29 0r 3/16? This makes sense, the IP sent volume below 500 daily, except on 1/12. The Domain data points existing on 12/29, 1/12 and 3/16 is the intriguing part.

Perhaps the Domain volume threshold is lower? Anything above 50/day? Maybe this confirms how much importance Gmail places on the Domain (DKIM signed domains)? Engagement play a part there…maybe?

So, what does this all mean?

Domains are looked at differently. Google has long said that they have thousands of signals to determine where to deliver an email. I suspect signals for a Domain will continue to carry a heavier weight.

Let’s not try to game Gmail’s system, why even try? Instead let’s understand the importance of reputation on the sending Domain. Showing Gmail that your Domain is sending wanted mail is the only true way to have a strong influence on Gmail’s filters.

Back to nerding out...


  1. Thanks for sharing this info, Brian. Do you know, or does anyone else, whether their Postmaster Tools include data for messages sent to domains using Google Apps for their email service (as opposed to

  2. That is a great question, I am not sure to be honest. I do know that in the situation I presented above, the sending volumes were so small on certain days even with Google App data aggregated it wouldn't have exceeded the 500/day and delayed mail wouldn't have influenced it. I think the conditions were just right for me to notice the differences.


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