Yes, I know your POV. If you are right, then this proposal will go the way that most proposals have gone: to the reference library. If not, we may see this flag in the nodelist some day. Time will tell.
AV> One single not-really-a-problem raises only when the nodelist line AV> contains INA:f.q.d.n flag, as the old mailers may be unable to detect AV> EAI_ADDRFAMILY returned by getaddrinfo() or NO_ADDRESS returned by AV> archaic gethostbyname()
AV> Once faced, that may be solved by either: AV> 1. Updating the mailer.
Which will not be possible for many mailers.
AV> 2. Checking that manually.
The idea of the nodelist is that mailers can find the required information without human intervention.
AV> So leaving it up to sysops seems to be the best solution. And, of AV> course, we should recommend checking for EAI_ADDRFAMILY to the AV> developers.
Of course. But that won't help the syops that use abandonware.