The following may be "old news" or obvious. However, it was new to
me so I decided to share it on the outside chance it might help someone
else. Also, it would be interesting to know if something like this will
work in Mailer 2.0 or if maybe it won't even be needed... ;-)
Many users have Internet addresses which are not directly on the
Internet but are served by "mail exchangers. Such hosts are described
in MX records in the Domain Name Database on the Internet.
As we know, the IBM VM TCP/IP product does not support MX records
for its gateway function at this time. When we add users to a list
we have to "look up" the mail exchanger and use the % hack to directly
route mail there. For example, if you query the name server (and many
have no way to do that) for ADOBE.COM, you find that it has an MX record
listing SUN.Com as a mail exchanger. So I could direct mail to [log in to unmask]
with [log in to unmask] .
However, when users send mail commands from an "MX" site to LISTSERV,
the gateway is often not shown in the "From:" address. Therefore, if
[log in to unmask] sent a command to LISTSERV, LISTSERV would try to answer
by sending mail to [log in to unmask] which our gateway won't handle right
now. For subscriptions I had learned to try the gateways at several sites
which COULD handle MX records or to find the MX handler and route the mail
there.
Yesterday I decided that there must be a way to "hard code" the MX
sites I knew about in MAILER 1.25. I realized that this was similar to
what we did to fix up mailer for the ".OZ", ".DEC", and ".SPAN"
pseudo domains (they had hard coded routes in the MAILER I think).
I looked through the lists we run here and from the couple thousand
entries picked those that ended with routes via some of the gateways
I had used to get around the MX problem. I then researched these a bit
using the VM TCP/IP resolver and the domain name database to find resonable
attempts as to what domains I knew about which were in MX records and
where the handlers for them were.
I coded the MX Handlers I knew (some like Relay.CS.NET are used by
more than one site) as variables at the begining of the MAILER MTPLATE
file. For example, [log in to unmask] would be used as a "parm"
on the BSMTP exit for sites whose MS records point to Relay.CS.NET.
(Note: There is a "preference value" listed in front of the mail handler
in the RDATA portion of the MX record. While the lower the preference
value the better, I have found it might take some experimenting to find
the best handler to use).
Then I added an entry in the DOMAINS section (BEFORE the %domains
record) which listed the domain or host which was in an MX record
as the DOMAIN, and the variable defined above as the "parm" to the exit.
MAILER (well the exit I guess) automatically will tack on the destination
without it having to be coded by the mail sender.
So, if I now send mail to [log in to unmask], MAILER here will find
the entry in the resulting MAILER PROFILE which has a parm of "%viaSUN"
and will build the destination address as: [log in to unmask] .
I have tested this with several sites that I have had problems with
in the past and it works. What is nice is that I am now even
able to REPLY to those sites without having to manually fix the
address!
These changes do NOT inform LISTSERV that the MX domains should be
routed to the local MAILER. Remember that LISTSERV uses DOMAIN NAMES
in some of its routing decisions. But we have modified the DOMAIN NAMES
so LISTSERV knows that the basic 1st level domains (.EDU, .COM, etc.) go
to our gateway here. And this does seem to work (I tried it with
DIST1, DIST2, and no Mail-via at all but only for one site...).
Below are the parts of the MAILER MTPLATE that I coded here. I make
NOT guarantees about whether this will work anywhere else (or if it
always works here even...). I would like to know the hazards or
pitfalls of this if others see those... I took an experimental
approach which may miss something obvious...
Obviously full MX record support is the goal, but this seems to be
helping me in the mean time... It would be important to verify the
addresses every so often - some of them do change (for example,
I found one site which was now on the internet in my testing).
-----------
Marty Hoag
ND Higher Education Computer Network US Mail: NDSU Computer Center
Phone: (701)-237-8639 PO Box 5164 / UCCS
Bitnet: NU021172@NDSUVM1 (NOTE 0 = ZERO) Fargo, ND 58105
ARPA: [log in to unmask]
UUCP: ...!psuvax1!NDSUVM1.BITNET!NU021172
----- Things I coded in MAILER MTPLATE to try this -----
(Mailer 1.25)
... Other stuff at the front of MAILER MTPLATE for Mailer 1.25. ...
POSTMAST=INFO@NDSUVM1 ; Person for mail system questions
BITINFO=INFO@NDSUVM1 ; Bitnet Info id(?)
; (see "SPECIAL:" table below)
... etc. ... ; SPAN/DEC/OZ "fixes"
[log in to unmask] ; SPAN domain
[log in to unmask] ; DEC domain
[log in to unmask] ; OZ domain
;
; A few MX Handlers I know about...
;
[log in to unmask] ; .sq.com (eg.).
[log in to unmask] ; via CSNET (eg. NWBOE1.BOEING.COM
[log in to unmask] ; via SUN.COM (eg. ADOBE.COM)
[log in to unmask] ; eg. grebyn.com
[log in to unmask] ; eg. super.org et al
[log in to unmask] ; eg. eg.ti.com
[log in to unmask] ; eg. amh.cs.umass.edu umass.edu
INCOMING:
... etc. ...
DOMAINS:
;
; Domain name Node Userid Exit Type Parm
; ---------- -------- -------- -------- ---- --------
SQ.COM NDSUVM1 SMTP BSMTP 3 %viaUIUC
ASU.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
.BOEING.COM NDSUVM1 SMTP BSMTP 3 %viaCS
FMC.COM NDSUVM1 SMTP BSMTP 3 %viaCS
INTEL.COM NDSUVM1 SMTP BSMTP 3 %viaCS
NMSU.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
NMT.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
NORTHEASTERN.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
NTT.JP NDSUVM1 SMTP BSMTP 3 %viaCS
SCAROLINA.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
SP.UNISYS.COM NDSUVM1 SMTP BSMTP 3 %viaCS
TEK.COM NDSUVM1 SMTP BSMTP 3 %viaCS
UTD.EDU NDSUVM1 SMTP BSMTP 3 %viaCS
ADOBE.COM NDSUVM1 SMTP BSMTP 3 %viaSUN
PORTAL.COM NDSUVM1 SMTP BSMTP 3 %viaSUN
NSC.COM NDSUVM1 SMTP BSMTP 3 %viaSUN
SUPER.ORG NDSUVM1 SMTP BSMTP 3 %viaSUP
.TI.COM NDSUVM1 SMTP BSMTP 3 %viaTI
UMASS.EDU NDSUVM1 SMTP BSMTP 3 %viaUMA
GREBYN.COM NDSUVM1 SMTP BSMTP 3 %viaUMD5
%domains
.DEC NDSUVM1 SMTP BSMTP 3 %viaDEC
.OZ NDSUVM1 SMTP BSMTP 3 %viaOZ
.SPAN NDSUVM1 SMTP BSMTP 3 %viaJPL
... etc. ...
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