[SUMMARY]Conflict between sendmail 8.9.0 anti-relaying and POP mail

From: Larry Griffith <larry_at_garfield.wsc.mass.edu>
Date: Tue, 16 Jun 1998 18:20:25 -0400

Dear Managers,

     Lots of replies on this one:

Allan E Johannesen <aej_at_WPI.EDU>
Dave Tetreault <davet_at_uriacc.uri.edu>
Hans Ranke <Hans.Ranke_at_ei.tum.de>
Ann Cantelow <cantelow_at_athena.csdco.com>
Paul A Sand <pas_at_unh.edu>
Nathan Grass <NathanG_at_UTS.Itron.com>
Mike Iglesias <iglesias_at_draco.acs.uci.edu>
Tom Smith <smith_at_semail.mro.dec.com>
Debby Quayle <dquayle_at_hamilton.edu>
Bugs Brouillard <bb1_at_axe.humboldt.edu>
"Lauzier, Edward" <LauzierE_at_hanscom.af.mil>
"Randall S. Winchester" <rsw_at_Glue.umd.edu>

and maybe some still to come.

    The gold star goes to Dave and Paul, who pointed out this URL to
me:

Look at http://www.tech-net.net/technical/ under POP Authentication.

    That describes exactly what I want! I tried implementing it (a
few tweaks to get from FreeBSD to DU) and it seems to work fine! If I
encounter any future problems I'll post again.

Other suggestions:

i) Use the ISP's MUA (mail user agent) to reply. Should work, but it
requires that users switch from their POP client to the ISP MUA and
back just to reply to mail (It was pointed out by several respondents
that Netscape does allow you to specify two different servers, which
avoids the switching). Also unless the reply address is set correctly
any reply comes back to the wrong place. My users wanted everything
to go through the College address, not the ISP address.

ii) Claus Assmann's page of sendmail cf code tricks. Since I checked
out the URL above first, I didn't look at this. Also the following
URL was suggested (I didn't look at it either):

    http://spam.abuse.net/tools/smPbS.html.

iii) Several people suggested restricting relaying to local users or
just a few ISPs. That would lock out most of my POP users; they come
from a wide variety of ISPs outside our domain.

     I also have to apologize for some sloppy wording in my original
post. Several respondents thought I was trying to use the POP
protocol to send mail and pointed out that POP only reads mail; SMTP
must be used to send mail. Sorry for the confusion; I wasn't trying
to use POP to send mail. It's just that many common POP clients
(e.g. Netscape Mail) are also MUAs; it would be nice if once one was
POP-authenticated with a POP client, that same client could be used to
send mail as an SMTP client. That's what we couldn't do, because
sendmail treated it as a relay.

     Thanks to all who replied!

                                                Larry

============================================================================
Larry Griffith Dept. of Computer & Info Science
larry_at_garfield.wsc.mass.edu Westfield State College
(413) 572-5294 Westfield, MA 01086 USA
PGP public key available at: http://garfield.wsc.mass.edu/dcis/griffith.html
============================================================================

Original post:

Dear Managers,

        I finally got sendmail v.8.9.0 compiled and running, but I've
run into a new problem. By default sendmailv890 refuses to relay
mail, generally a good thing that I would like to keep. However, POP
mail users complain that any mail they try to send is treated as a
relay and refused.

        Since this is a college, many POP users are students coming in
via their ISPs. Hence they are not inside our domain. Further many
of the ISPs use dynamic addressing, so I would have to authorize large
domains for relaying, which is almost as bad as allowing promiscuous
relaying. Is there any way to get sendmail to authorize relaying
based on service (e.g. POP) rather than based on domain or IP address?
I can't find anything in the sendmail documentation.
Received on Wed Jun 17 1998 - 00:21:26 NZST

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