[ale] dialup and sendmail

[Jeremy T. Bouse]

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	Another thing you may need to check out is whether your ISP allows
port 25 connections to hosts other than to their mail server... that is a
strategy some ISPs are taking to combat spam since it forces the user to
use their mail server which leaves a log which they can then hold the
customer accountable for... For instance our network restricts all port 25
connections from dial-up equipment to the corporate /24 (Class C) network
which our mail servers all reside on... I know it's an arcane way to deal
with it but until the spammers either die or walk off the face of the
planet it's the best way to keep people accountable for their actions...

	Respectfully,
	Jeremy T. Bouse
	Sr. System Administrator

On Thu, 4 Feb 1999, Joe Bayes wrote:

> Date: Thu, 4 Feb 1999 20:43:39 -0500 (EST)
> From: Joe Bayes <jbayes at occs.cs.oberlin.edu>
> To: ale at ale.org
> Subject: [ale] dialup and sendmail
> 
> 
> Let me make sure I've got this straight...
> 
> I'm stuck behind a dial-up connection from cnmnetwork.com. I'm able to
> send mail locally on my machine, and I'm able to send mail to users at
> cnmnetwork.com. However, mail sent to anyone else on the 'net
> disappears and is never heard from again. No bounce or anything, it
> just doesn't arrive. 
> 
> I took the stock sendmail.cf which comes with RH 5.2, and modified the
> entry: 
> 
> # "Smart" relay host (may be null)
> DSsmtp:smtp.cnmnetwork.com
> 
> which, as I understand it, should deliver all non-local mail to
> smtp.cnmnetwork.com, which will then handle fowarding it on to
> wherever it's supposed to go. If I telnet smtp.cnmnetwork.com 25 and
> send my message from there, it arrives as it should.
> 
> Before I changed the above entry in sendmail.cf, mail would accumulate
> in /var/spool/mqueue, presumably because my machine was trying to
> connect directly to the destination machine and the destination
> machine wasn't about to promiscuously exchange bits with some piddley
> dial-up machine. 
> 
> What am I doing wrong?
> 
> Another question: Why will random destinations exchange mail with
> smtp.cnmnetwork.com, but not my machine? Those destinations don't know
> who smtp.cnmnetwork.com is, any more than they know who I am, right?
> (Does this have something to do with MX records?)
> 
> Here's an entry from /var/log/maillog:
> 
> Feb  4 14:32:12 spoo sendmail[3883]: OAA03881: to=jbayes at cs.oberlin.edu, ctladdr=root (0/0), delay=00:00:03, xdelay=00:00:02, mailer=smtp, relay=one.cnmnetwork.com. [209.79.28.34], stat=Sent (ok 918167348 qp 16076)
> 
> Thanks loads,
> 
> --joe
> 

,-----------------------------------------------------------------------------,
|  Jeremy T. Bouse   -   SouthNet TeleComm Services, Inc.   -   www.STSI.net  |
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|  sysadmin at STSI.net   -   NIC Whois: JB5713    -    undrgrid at UnderGrid.net   |
|            /earth is 98% full ... please delete anyone you can.             |
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