Re: last call on smtp-8bittransport

[Jim Knowles <jknowles@xxxxxxxxxxxxxxxxxx>]

Hi Neil,

> But the error is not adequately defined.  If it is not defined, an
> implementation is forced to either:
> 
> 	(a) treat SIZE as a NOP, accept the full message, and take
> 	    size based action only when the true size is known.
> or
> 	(b) use guesswork, and sometimes refuse mail which might actually
> 	    be within range.

Yes, you can call a best-faith estimate guesswork.  Yes, mail may (very
rarely, I think) be refused when it should not be.  Of course, the client
chose to use the SIZE verb in this case, which means the client considers
the benefit of this usage to outweigh the possible cost.  Well, we pretty
clearly disagree on which option to choose here, except that "use
guesswork" should be replaced by "accept what the client told you".

Since I don't buy your choice of NOP, I can't accept your arguments about
the uselessness of the EHLO response.  I think John Klensin gave a pretty
thorough answer when you first claimed that the EHLO response was useless.
He specifically denied that it was in any way OK to just dump the internal
verb table.  Listing SIZE means that the server will make a decision based
on the SIZE argument and its own known limit.  I don't understand how this
is meaningless.

> Now, a few years down the road, suppose somebody tries to do something
> useful with EHLO.  Then they discover that there are hundreds of thousands
> of hosts with just such an implementation, so that the EHLO response is
> partially bogus.  No amount of screaming.  It will be back to the drawing
> board, to create something that works properly.  In the meantime new
> software will still have to honor EHLO for backwards compatibility.

Perhaps a line should be inserted into the draft:

	Do not just dump the internal verb table.

There is already an explanation of meaningful support which I think is
entirely reasonable.  It can certainly be beefed up.  I'm not sure that
would satisfy you.

> You would be much better off with just EMAL, and dropping EHLO and SIZE.
> This is enough to handle 8bit mail, so meets the immediate needs.  Leave
> EHLO and SIZE till the future when a more forward looking design can be
> found.

A number of folks in the WG disagree and think SIZE is useful and EHLO is
meaningful.  These concepts have been part of WG discussion for at least
a year, so dropping them now does not seem appropriate.

Jim