Hi,
I am quite new to sendmail and thus please excuse me for my lame
questions. I've recently configured a mail server at my organization
using sendmail (smtp server), dovecot (pop3/imap server) and
squirrelmail (webmail client). The setup of the entire mail system is
as follows:

We have a mail exchanger which is also our primary dns server for
outside world. It's through this dns server that our servers are
resolved from external world. Let's call this server dns1. This
server is also responsible for sending mails to outside world. Trend
Micro Officescan is also running on this server which scans every
incoming and outgoing mail. Some spam protection softwares like Spam
Assasin and SPF Milter have also been configured on this server.

There is this newly configured mail server with sendmail , dovecot and
squirrelmail running on it. Let's call it mail1. The mails from this
server are relayed to dns1. The user accounts on this server are
authenticated against an LDAP server.

LDAP server is holding all the information about a user like UID, GID,
Home Directory, Shell information etc. The passwords are also stored
on this server itself.

Now every user can login in properly to the system. The mails are also
moving in and out smoothly. The problem is that if a user sends a mail
to an address say xyz [at] abc.com and abc.com is a non-existent domain,
then mail is not bounced back to sender but instead to root [at] dns1, i.e.
root account of my mail exchanger server.
However if a mail is send to xyz [at] abc.com and abc.com is resolvable but
xyz is not a valid user on the domain, then mail is bounced back to
sender.

If you could please help me out on this front, it would be really kind
of you as I'm really stuck with this problem at the moment.

Regards,
Maxcoder

Maxcoder wrote:

> The problem is that if a user sends a mail
> to an address say xyz [at] abc.com and abc.com is a non-existent domain,
> then mail is not bounced back to sender but instead to root [at] dns1, i.e.
> root account of my mail exchanger server.
> However if a mail is send to xyz [at] abc.com and abc.com is resolvable but
> xyz is not a valid user on the domain, then mail is bounced back to
> sender.
>
> If you could please help me out on this front, it would be really kind
> of you as I'm really stuck with this problem at the moment.

All information you need is probably available in the log files of
both servers, as well as in the bounce message that was sent to root.
You didn't show any of that information so all we can do is guessing.

This looks like dns1 not being able to send a bounce message to the
proper address so it will send a "double bounce" to postmaster and
postmaster is commonly aliased to root.
Again: see your logs and the actual bounce message for the reason
why the bounce message could not be delivered properly in the
first place.

Regards,

Kees.

--
Kees Theunissen.