That bit is easier for me than for you, perhaps, since gmail implements about four RFCs I've written ;) That bit isn't the MSB, though. The MSB is that they do

That bit is easier for me than for you, perhaps, since gmail implements about four RFCs I've written ;) That bit isn't the MSB, though. The MSB is that they do care about fixing interop problems with everyone, they just don't read mail from randoms. I think they assume is that if a problem is their fault it will show up on their monitoring graphs, and watch their error graphs instead of their postmaster inbox.