Salut, Kurt,

On Wed, 26 Mar 2008 15:03:40 +0100, Kurt A. Schumacher wrote:

What about the most stupid wanabe Spam-fighter which are very unhappy as in place (e.g. the third-party service provider systems acting with some SC subsidiaries...) which high rate valid messages if certain brain-dead conditions like PTR not matching MX don't match?

2 points about this.

1. it is highly unlikely that these stupid wannabe SPAM filters get the response containing so many PTR records right. It is most likely that either the software blows up or that it only ever considers the entry it receives first.

(Most likely the software blowing up will not even be remarked but instead the mail will be rejected silently.)

2. Since a lot of people use personalized domains now in their mail addresses (me@first.lastname.ch, bla@pascual.garnier.name, whatever), the people who use such a setup will be strongly discouraged very quickly and be forced to drop it, since they want to still be able to send mail, most likely. We should not make such stupid moves just to encourage them to adopt such a setup.

Under the line, it is likely not a DNS issue, but the inability by some mail or AS systems resolving lists. Suspect my servers will fail, too. Xaver, pls send private reply for a test from that system, anytime.

It is also a DNS issue, depending on the number of results returned; the size of a DNS/UDP response is limited to 1 UDP packet, which again is limited in size. Not everyone uses DNS over TCP, and it is unlikely to be adapted just because of such a stupid and useless SPAM filtering measure.

Tonnerre