RE: Unknown mechanisms

> -----Original Message-----
> From: Frank Ellermann [mailto:[email protected]]
> Sent: Saturday, September 03, 2011 4:51 AM
> To: [email protected]
> Subject: Re: [spf-discuss] Unknown mechanisms
> 
> > Yes, it's in the ABNF, and the definition of "permerror"
> > basically covers it.  Is there harm in explicitly
> > connecting the two?
> 
> Not directly, but I recall that we had *big* difficulties
> to limit the size (in pages) of this beast.

I'm not advocating adding "pages".

> Your proposal could result in new text like this:
> 
> | Note that there are no "unknown mechanisms", because this
> | would | result in a syntax error while parsing a policy,
> | or, if it were explicitly allowed, in PERMERROR results
> | with older implementations, and in different results with
> | newer implementations either supporting or ignoring such
> | mechanisms.  Therefore a new version different from v=spf1
> | is REQUIRED for the introduction of new mechanisms.

Or, the one sentence I already proposed:

"An SPF-aware receiver encountering an unknown mechanism MUST return a 'permerror' result."

> If you have a shorter/clearer idea to explain the issue of
> unknown mechanisms in prose, shoot.

Shot taken.