[65519] in North American Network Operators' Group
Re: incorrect spam setups cause spool messes on forwarders
daemon@ATHENA.MIT.EDU (Randy Bush)
Mon Dec 1 13:53:19 2003
From: Randy Bush <randy@psg.com>
Date: Mon, 1 Dec 2003 10:50:51 -0800
To: Suresh Ramasubramanian <suresh@outblaze.com>
Cc: nanog@nanog.org
Errors-To: owner-nanog-outgoing@merit.edu
>> is the following a general problem, or just one i am seeing?
>
> Verizon does SMTP callbacks, connecting back to the MX of the envelope
> sender and trying to verify that the user exists
>
>>
>> 2003-12-01 10:09:05 1APbBa-000Ork-DY == foo.user@verizon.net <foo@psg.com> R=lookuphost T=remote_smtp defer (0): SMTP error from remote mailer after MAIL FROM:<nikkiadamczyk@gerbangmail.com> SIZE=5365: host relay.verizon.net [206.46.170.12]: 450 Requested mail action not taken-Try later:sc004pub.verizon.net
>>
>
> So this would connect to the MX of gerbangmail.com and try to verify
> that whatever@gerbangmail.com exists.
>
> gerbangmail.com. 5h55m6s IN MX 0 sitemail.everyone.net.
>
> If the MX (sitemail.everyone.net) doesn't respond fast enough for
> verizon, their tester times out, and the message gets 4xx'd.
interesting but utterly irrelevant. the question was not how
verison decided it was spam. the point was that their server
returned a 450 as opposed to a 5xx (550 looks good), and this
causes net damage.
randy
