[Wylug-discuss] Re: SMTP standards (was Please confirm...)

[Peter Corlett]

James Holden <wylug at jamesholden.net> wrote:
> Peter Corlett wrote:
>> James Holden <wylug at jamesholden.net> wrote:
[...]
>>> If you deny access based on an invalid HELO, you *will* lose legitimate
>>> mail, and you *will* be breaking RFC 2821 (sec 4.1.4).
>> It's not lost, it's just not being accepted. That's a subtle, but
>> important distinction.
> It's lost if it never hits your mailbox when it should have done.
> Subtlties are unimportant. Your users won't get mail which they should
> have done. Try explaining that to them when they don't receieve that
> important order.

No, a message is lost if a SMTP server chooses to drop the message after
accepting it and taking responsibility for it. It is not lost if the server
chooses to give a 5xx response. The sending SMTP server retains
responsibility for not losing the message. If the sender is broken and
subsequently loses the message, that's their problem.

RFC 2821 places no obligation on a server to accept arbitrary messages. It
is even permitted to not provide a "postmaster" mailbox under certain
circumstances.

>> The contents of RFC 821 are moot, as it is obsoleted by RFC 2821. RFC 821
>> should only be read if one is looking for a historical perspective, and
>> definitely not as a standards document.
> Correct, hence my inclusion or 2821.

I was actually pointing out that you shouldn't have bothered to include RFC
821, but as usual, people on this list have missed the point.

--
[About a discussion of heavily customised cars.]
I thought they were talking about cheap whores - smelly, ugly, brightly
coloured, waste of money, and got a cock inside them most of the time.
					-- Will Hargrave in uknot