Quoting Tim Connors (tim.w.connors@gmail.com):
Wouldn't the market solution to be to continue doing things from the technically correct point of view on infrastructure we maintain, and ignore companies that don't?
yahoo senders, sending to a mailing list can't have their mail received by google recievers, and it's because yahoo are being silly regarding choice of standards? Easy. If the yahoo customers care about being listened to, then they'll change providers.
It's a cost-benefit calculation, I guess. Today Yahoo, tomorrow who else? Also, who else today, honestly? I'm honestly not sure. FWIW, I am _not_ (so far) doing the described sort of transformation on any of the Mailman mailing lists I administer for BALUG (San Francisco), SVLUG and CABAL (Silicon Valley), or others, and I've not yet heard complaints or seen any problems. Just a data point.