full-disclosure - Gmail blacklisted by Full-Disclosure

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Date: Mon Jun 20 18:21:07 2005
From: greed at pobox.com (Graham Reed)
Subject: Gmail blacklisted by Full-Disclosure

Valdis.Kletnieks@...edu writes: 

> Complain to GMail - it's saying that a 'MAIL FROM:<>' is invalid, when
> in fact its the *mandatory* way of sending bounce messages. RFC2821, section 6.1:

That may be what the error message from the blacklist claims to say, but 
that's not what the "evidence" provided on the blacklist's website says: 

<URL:http://www.rfc-ignorant.org/tools/detail.php?domain=zproxy.gmail.com&su 
bmitted=1116709803&table=dsn> 

<postmaster@...oxy.gmail.com>: connect to zproxy.gmail.com[64.233.162.200]:
   Connection timed out 

So, of course MAIL FROM:<> fails.  MAIL FROM: <validuser@...il.com> will 
also fail, as will MAIL FROM: <bogususer@...il.com> or MAIL FROM: invalid 
syntax. 

A quick check with good ol' telnet confirms that Connection timed out is, 
indeed, the problem.  So it's not that quick a check.... 

It is entirely possible that these machines are interior to exterior relays; 
they are not MX nodes.  Trying to deliver to these machines rather than the 
advertised MX seems just... well, prone to failure at best. 

There is no requirement I'm aware of that an SMTP sender also be an SMTP 
receiver.  If your MTA accepts the message and then finds out it needs to 
bounce it, you bounce to the address provided in MAIL FROM:.  You no longer 
care about the HELO/EHLO host, and besides, what username would you use on 
that host anyway? 

DNSbls are good, but I'm not sure that DNSbl is well-run, though I do 
approve of its intent.