Domain Groups?

I’ve played around with this for several years and wanted to get some community feedback.

We often look at opens, bounces, and other metrics at the top domains to monitor deliverability. But looking at just standalone domains misses "Domain Groups" . The best example is RoadRunner, which often does not get to the top of any top domains list because there are dozens of domains at * and But when you aggregate all those different RoadRunner domains together it often will percolate to the top. And when we are asked by clients what the largest domains are, if we look at just address we don’t take into account and addresses.

Here is the list of domains we have considered merging into "Domain Groups"  for these reports. Mostly interested in merging domains that we are 100% certain are using the same spam filters. Any thoughts on this idea?

RoadRunner (*,
Gmail (,
Hotmail (,,
UnitedOnline (,,
Comcast (,,
AOL (,,,,,
IAC (,,
Yahoo (,,,,,, all the international domains listed at!_Mail#Email_Domains)


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