IP Range Grouping verified
The same grouping idea, applied to the address ranges of the receiving servers.
In detail
Where MX grouping collects domains by who handles their mail, this collects receiving servers by where they live. It catches the case MX patterns miss: a provider whose MX names differ but whose servers share a range. Both exist because the unit a receiver enforces limits on is rarely the domain — it is the infrastructure behind it, and this screen is the second way to name that infrastructure.