[Cryptography] Strong DNS Names

[Viktor Dukhovni]

On Sat, Sep 10, 2016 at 02:03:49PM +1000, Dave Horsfall wrote:

> On Fri, 9 Sep 2016, Tom Mitchell wrote:
> 
> > It is interesting that Google's Gmail allows a name+suffix.
> 
> Isn't that part of the SMTP standard?  It works against Sendmail as well.

No, address extensions are not part of any standard.  They are an
ad-hoc syntax introduced in the Andrew Messaging System (AMS) at
CMU in the early 80's.   The {8,28,53}2{1,2} series of RFCs strive
to avoid prescribing any particular structure or semantics to the
"localpart" of an email address, even to the extent of not specifying
the widely implemented (and incorrectly assumed to apply everywhere)
case-insenstive treatment thereof.  The interpretation of address
localparts is quite intentionally *local*.  When (double) quoted,
and/or sprinkled with quoted-pairs where appropriate, localparts
can contain pretty much anything.

AMS used "+" as the recipient delimiter (Postfix name for the
separator).  Later, in the 90's, DJB observed that "-" is more
typically tolerated by overly strict address parsers, particularly
in HTML forms, and so used "-" as the recextensively in Qmail.

Postfix documentation tends to suggest "+", which seems to be more
common, but the recipient delimiter is empty (disabled) by default,
and each site can choose whatever recipient delimiter suites its
needs best.

-- 
	Viktor.