From: Colin Fitzpatrick (colin at domain xsynergy.com)
Date: Wed 12 Jul 2000 - 00:31:58 IST
Q3.22 -- How do I configure sendmail not to use DNS?
Date: March 24, 1997
Updated: April 6, 2000
In situations where you're behind a firewall, or across a dial-up line,
there are times when you need to make sure that programs (such as
sendmail) do not use the DNS at all.
With older releases of version 8 sendmail (8.7 and earlier), you need to
recompile the binary and make sure that "NAMED_BIND" is turned off in
With versions 8.8 and later, you change the service switch file to omit
"DNS" and use only NIS, files, and other map types as appropriate. More
information about the service switch file can be found under the
ServiceSwitchFile option in §5.6 (Options) of the Installation and
Operation Guide and all of §4.9 (Name Server Access).
Also, starting with 8.9, it may help to include the following in your
Note that you'll need to forward all your outbound mail to another
machine as a "relay" (one that does use DNS, and understands how to
properly use MX records, etc...), otherwise you won't be able to get
mail to any site(s) other than the one(s) you configure in your
/etc/hosts file (or whatever).
Hope this helps.
Conor Daly wrote:
> Just browsing through mutt documentation and notice that it uses
> sendmail directly. Now, I'm using an smtp server (hobbiton) to queue
> email until an internet connection comes up but from mutt, sendmail
> tries to deliver immediatly.
> I have "hold expensive=true" in /etc/sendmail.cf
> I've used Donncha's install-sendmail script to set up my sendmail
> configuration and all works fine from a client but I'm testing mutt on
> the server. Can't check on the client at present 'cos I'm telnetting to
> the server from the Windows side on the client and I need to look at the
> config on the Linux client which isn't booted at present.
> I suspect I need to do something like point sendmail to "hobbiton" as
> it's smtp server even from hobbiton or something recursive like that.
> The hobbiton server is set up with my diald virtual IP address as it's
> default route while the clients have hobbiton as their default route.
> sendmail on hobbiton listens to 192.168.1.0/24 and queues any mail
> coming from there. It also listens to 127.0.0.1 but seens to try to
> send immediatly from there. Is it something like this:
> sendmail is running as a daemon on hobbiton and listening for client
> mutt is invoking another sendmail process to send its mail and since the
> default route for the server is not localhost, the already running
> sendmail is not picking up the mail.
> imap support in mutt is fragile at present so I feel safer using mutt
> over an rsh or rlogin to the server.
> If I run mutt from a client, I suspect the server's sendmail will pick
> up and queue outgoing email sent by mutt.
> Confused eh? Me too.
> Conor Daly
> (Still haven't figured out how to append my .sig with mutt...)
-- Colin Fitzpatrick colin at domain xsynergy.com
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