[Info-vax] bizarre SMTP problem

[Arne Vajhøj]

David J Dachtera wrote:
> Steven Underwood wrote:
>> "Bob Eager" <rde42 at spamcop.net> wrote in message
>> news:176uZD2KcidF-pn2-PXhqF33pn2BN at rikki.tavi.co.uk...
>>> On Thu, 9 Apr 2009 19:57:15 UTC, JF Mezei
>>> <jfmezei.spamnot at vaxination.ca> wrote:
>>> Then it appears to be a bug, since '+' is perfectly valid as a character
>>> in an email address, as per RFC 2822 section 3.4.1.
>> That may be, but there are lots of systems that do not honor plussed
>> addressing.  My mail provider (SpamCop.net) allows for plussed addressing
>> but many web based systems find those addresses to be illegally formatted.
> 
> Such characters are not valid in UN*X usernames for many flavors of
> UN*X, nor would it be allowed on VMS. So, it seems likely that an
> attempt to verify the existence of such a user on a VMS or UN*X
> receiving end would be likely to fail.
> 
> The protocol itself my not disallow it, but is that a valid username on
> the receiving system, and if so, how is that validated?

The part before the @ is not necessarily a username. Today it is
practically never a username. 15 years ago it did not have to be
a username (PMDF supported firstname.lastname back then).

Arne