SMTP addresses in <>

Sat Jan 5 16:21:47 UTC 2008

> > Our mail servers reject connections that don't follow the RFC. Am I
> > wrong to do this?
> Seth,
> RFC 1122 (Requirements for Internet Hosts - Communication Layers)
> section 1.2.2 (Robustness Principle):
>
>                 "Be liberal in what you accept, and
>                  conservative in what you send"

I would say this quotation of RC1122  1.2.2 seems a little bit out of context.
"being liberal in what you accept"  in terms of such egregious errors
as a mailformed
destination address does not mean you necessarily pass the message on.

The robustness principal doesn't say you have to correct the error and
accept the message,
continuing normally, as if there was no error, it says you're prepared for it

To be robust, your SMTP server implementation must not crash if a user
omits the
angle brackets,  it must be prepared to accept the malformed text, and
respond accordingly,
I.E. Refuse the message, with an error response, if it doesn't
recognize the proper destination
format.

The following paragraph of RFC1122 states:

"Software should be written to deal with every conceivable error, no matter how
unlikely; sooner or later a packet will come in with that particular
combination of errors
and attributes, and unless the software is prepared, chaos can ensue.

In general, it is best to assume that the network is filled with
malevolent entities that will
send in packets designed to have the worst possible effect.  This
assumption will lead to
suitable protective design, although the most serious problems in the
Internet have been
caused by unenvisaged mechanisms triggered by low-probability events;
mere human malice would never have taken so devious a course!
"

--
-J