Our responses seem to have crossed...
> > > I am wrong, but it seams that extending VRFY command is more
> > > appropriate for the purpose than using RCPT.
> > Hmm. _That_ is an interesting idea, since we have always
> > permitted VRFY to do somewhat more poking around in real time
> > than one might normally expect of RCPT (where "poking around"
> > efforts more often result in a 250 code and an email rejection
> > if needed).
> If I understand both your comments and Keith's suggestion, the key is a
> separate command.
> It, too, find that aesthetically preferable. The problem is with efficiency.
> A separate command means 2 commands per recipient and it means at least one
> synchronization event, between issuance of this new command and issuance of
> the first RCPT-TO.
You can avoid the need for additional round trips by batching all the
capabilities queries with the first RCPT TO. But this results in a rather sharp
rise in implementation complexity.
> That's quite a bit of overhead, for something that frequently will have no
> effect on the content being transferred.
Indeed. The average number of recipients for legitimate mail does tend to be
quite small, which implies we're optimizing the uncommon case here.
Ned
