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RE: [TCLUG:2372] Sendmail, Smail, and private networks



> Now, I'm dialing up with PPP to my ISP, and I'm probably getting a
> machine name of dial-upXXX.soncom.com.  My local private domain is not
> published to the net "icewall.org".  However, the default config for
> smail is to make my "visible_server" as "wookimus.icewall.org".  Isn't
> this type of config going to cause problems with receiving SMTP servers?
> Do I need a visible_server name?  If so, what should I use?  I'm really
> confused about this stuff and the HOWTOs don't help.

	I don't know, but I don't *think* you'll have any problem.  Here's a way to
test:
	In case you didn't know, you can test sendmail by telnetting to port 25 on
the sendmail host.  Here's a typical session: (I've marked the stuff you
type with a ">")

	220 mail.foo.com ESMTP Fri, 27 Nov 1998 15:18:39 -0600 (CST)
>	HELO foo.com
	250 rattler.ccecu.com Hello user.foo.com [192.168.100.100], pleased to meet
you
>	MAIL FROM: "me@foo.com"
	250 "me@foo.com"... Sender ok
>	RCPT TO: "recipient@bar.org"
	250 "recipient@bar.org"... Recipient ok
>	DATA
	354 Enter mail, end with "." on a line by itself
>	This is a test
>	of sendmail
>	.
	250 PAA14870 Message accepted for delivery
>	QUIT
	221 mail.foo.com closing connection

	Here's how I *think* this should work out.  We assume that "foo.com" is
your home lan -- it doesn't need to be registered so long as all the
computers on your lan agree on the name.  Try this from your intended home
sendmail server

----------------
	Example a:  You telnet to port 25 on localhost with mail for
recipient@bar.org.  Provided that localhost is properly configured, your
message is accepted.

	Example b: You telnet to port 25 on mail.bar.org (or whatever the bar.org
MX record points to) with mail for recipient@bar.org.  Your mail is accepted
because it is for a user local to bar.org, regardless of where it came from
(unless the remote system does anti-spam filtering and you're on the
"refuse" list).

	Example c: You telnet to port 25 on elohim.dogma.org (my reasonably
well-locked-down home server) with mail for recipient@bar.org.  You get a
"relaying denied" message and sendmail refuses to deliver the message.  If
you then specify the recipient as "root@elohim.dogma.org" it accepts the
message.
-----------------

	If the above examples work the way I've predicted on your unpublished
domain, this should work perfectly for pretty much everyone.
	Otherwise, your best option is to rig up sendmail to use the SMTP server
assigned to your dialup account as a forwarder, and contact your ISP to make
sure they'll allow you to bounce relay messages off of it.