VERP - Variable Envelope Return Path

[David Relson]

On Fri, 26 Sep 2003 01:22:09 +0200
Matthias Andree <matthias.andree at gmx.de> wrote:

> David Relson <relson at osagesoftware.com> writes:
> 
> > The VERP form is
> > {token1}-{token2}-{number}-{token3}={token4}@{token5}, as best I can
> > tell.  How much freedom does the mailing list have in setting token1
> > and token2?  Can they have embedded hyphens?
> 
> All that matters is that the mailing list driver (ezmlm, ezmlm-idx,
> Mailman 2.1, maybe some alpha version of majordomo) understands
> it. You'll typically see the list encoded in token1, and I'd guess the
> format doesn't support embedded hyphens. However, a different
> configuration (list or software) can use a different VERP format.
> 
> The VERP must be a) routable, b) parsed reliably by the list driver.
> 
> The point about VERP is to reliably identify a bouncing address no
> matter how obscure the error message is, ambiguity would defeat the
> purpose.

The lexer expression I'm using works for the VERP samples I've looked
at.  If/when incompatible formats are encountered, it can be changed. 
Remember the goal is reduce the number of singletons and create tokens
that'll help distinguish spam from ham.