9 ms·

By now I suspect you can simplify it down to just matching on the RHS for any domain registered to Yahoo.

• longwave 10y ago
  A number of ISPs have used Yahoo to provide mail services in the past, so it's probably not quite as straightforward as that.
  • manarth 10y ago
    And not just small ISPs, but major ISPs, such as BT (with 32% of the broadband market-share in the UK).