"David Lemson (Exchange)" <dlemsonat_private> writes: > connecting to you over and over: it sounds like if they were to fix their > inverse DNS entries, so you didn't give them a temporary error code, the > mail would succeed. This is not to say that what the SMTP Service is doing > is right, but there may be another way to solve this particular problem. > > Another solution, which you allude to, is for your server to issue a > permanent (5xx) code to a problem that will not get corrected on its own > (such as an invalid inverse DNS record). You miss the point - this could simply be that their DNS is down or unreachable in a timely manner so the lookup fails. When this produces an nonexistent entry it actually *does* often correct itself "on it's own" once the DNS server is reachable again. Similarly the invalid entry may in fact be corrected before the usual timeout and allow the mail to proceed. That's the whole point of returning 4XX. The only way your "solution" is a solution is to return 5XX errors for *ALL* situations that currently return a 4XX, otherwise we risk being DOS'ed by a poorly written server that doesn't treat SMTP errors right. And this isn't a solution - You lose mail that you shouldn't. So now I should lose mail on a transient DNS failure because microsoft distrbutes code that doesn't play SMTP nicely? I don't think so. The only solution is to fix the buggy code. and/or block access from sites running buggy code. -Bob
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:39:13 PDT