[svlug] Can't Receive

[Rick Moen]

Scott DuBois wrote:

>>  You would have gotten to this result a wee bit sooner if you'd done an
>> SMTP session manually using a telnet client, which is an essential skill
>> for  anyone attempting to run an SMTP host.  
> 
> I'm learning. 

If I may assist, here's an example, attempting to forge a fake sender,
and getting caught in that deception effort by the antispam 'callback' functions
built into the MTA on lists.svlug.org - resulting at the end in a 5xx
(544) SMTP permanent rejection response.  On the SMTP conversation
lines displayed, indicator tags 'LOCAL' vs. 'REMOTE' have been added on
the right hand sides of those transcript lines, as clues about which
lines are input vs.  which were responses.  (Those indicators were of
course not present in the original live telnet session.)


> 
Host 'gruyere' is the www.svlug.org virtual host at Linode.  The
delivery target is our mailing list server, lists.svlug.org .


rick at gruyere:~$ telnet lists.svlug.org smtp                            LOCAL
Trying 157.22.20.227...
Connected to lists.svlug.org.
Escape character is '^]'.
220 svlug.org ESMTP Exim 4.44 #1 Sat, 27 Dec 2014 00:18:39 -0800 - mm9 REMOTE
HELO www.svlug.org                                                     LOCAL
250 svlug.org Hello li3-98.members.linode.com [64.62.190.98]           REMOTE
MAIL FROM: <rick at deirdre.net>                                          LOCAL
250 OK                                                                 REMOTE
RCPT TO: <rick at svlug.org>                                              LOCAL
250 Accepted                                                           REMOTE
DATA                                                                   LOCAL
354 Enter message, ending with "." on a line by itself                 REMOTE
From: nobody-in-particular at fakedomain.gov                              LOCAL
To: Rick Moen <rick at svlug.org>                                         LOCAL
Subject: Yahrzeit                                                      LOCAL
                                                                       LOCAL
N799PA went down 46 years ago today.  That is all.                     LOCAL
.                                                                      LOCAL
550-Rejected after DATA: could not verify "From:" header address       REMOTE
550 nobody-in-particular at fakedomain.gov: Unrouteable address           REMOTE
quit                                                                   LOCAL
221 svlug.org closing connection
Connection closed by foreign host.
rick at gruyere:~$



> I got Postfix running on the home box too which required all the
> "twisty" port changing and using Google pop.a

Well, as I was saying to Michael Robinson, getting full-service SMTP
sending and receiving mail is quite enough work without also needing to 
creatively engineer around crazy port blocking and other strange
gratuitous obstacles.  If you want to learn it the way I did, start with
a full-service, no-ports-blocked real, routable IP address on which you
have a Real Operating System[tm] installed and have root authority.  All
those 'What if I have only grunt shell access on shared hosting?' and
'What if I need to work around control-freak firewalling?' and 'What if
I'm behind a NAT gateway?' compications are, at best, headache-inducing
advanced-skills problems.  You certainly don't want to _start_ with
those, and rational people pay money to avoid needing to deal with them
at all.

> I'm also noticing the differences between what Mutt and Mailutils
> build for metadata; Mutt is easier to deal with.

Dude.  Learn how to test your SMTP functionality using /usr/bin/telnet 
manual sessions to the target SMTP (=port 25/tcp) port.  That way, you
see all of what's going on.

And, as you doubtless already have seen, pay attention to SMTP logfiles.
MTA logfile entries are your friend.