Re: More about the SPF RRTYPE

On 15 August 2011 21:06, Murray S. Kucherawy wrote:

> Over on the exim-users mailing list, someone just complained that
> libspf2 tries for RRTYPE 99 (SPF) before 16 (TXT).  That’s what the
> standard says to do, but it also means some sites that firewall out
> unknown RRTYPEs cause clients to time out on the 99 before they try
> 16.  During that time, some SMTP clients time out altogether and
> try again later, and the mail ultimately never gets through.

> Maybe this isn’t news to anyone

Yes, but it is clearly something that should be addressed in 4408bis:

Apparently nobody intends to eliminate the ugly TXT abuse in v=spf1,
because it's years too late to try it, or IOW, the wannabe-experiment
failed to fix this.

Possible ways to improve that situation in 4408bis:

1 - try the SHOULD type 99 approach again, a PS could succeed where
    an "experiment" failed.
2 - give up, note that TXT is ugly but can't be changed, and that
    now is the time to drop SPF type 99 for the purposes of v=spf1.
3 - explain that practical EDNS0 limits could affect TXT where type
    99 still works, but that trying both queries simultaneously and
    pick the first answer is perfectly okay.

I didn't look into RFC 4408 for some years, but IIRC (3) is allowed,
or isn't it?

-Frank