Question : Linux Internal Email Server setup

Greetings everyone,

I am pretty new to Linux, DNS and Email altogether.  Furthermore, I was asked to setup a Linux internal mail server to replace our NT mail server for our office accounts only.  I checked out postfix and other options, but I decided I want to try learn and understand sendmail.  I have read through countless articles and docs trying to help myself better understand the process.  Nonetheless, trying to teach myself so much in such little time is taking its toll on me.  I suppose my major questions are as follows:

1. If no external mail capabilities are desired, do I still need to worry about setting up DNS?

2. What is the easiest solution for setting up MS Outlook 2k to work with this server? (we currently have Internet Mail that points to our external domain and Microsoft Mail pointing to our NT Server) I have tried pointing Outlook to the server's static IP, but no luck.

From what I understand--which may not even be sufficient--any of our office PCs should be able to look at the Linux server via port 110, and be directed to their personal user mailbox.  Sending mail should work the same except through port 25, the mail header should be read and then place the message in the desired user's mailbox.

I have Fedora Core 2 installed on the Linux box and we have a combination of Windows 2k and XP office machines all running Outlook 2k or 03.  I really appreciate any help you Linux experts can provide.  All of this is starting to give me a headache.  

Answer : Linux Internal Email Server setup

edit your /etc/mail/sendmail.mc and look for these lines

#######
dnl # We strongly recommend not accepting unresolvable domains if you want to
dnl # protect yourself from spam. However, the laptop and users on computers
dnl # that do not have 24x7 DNS do need this.
dnl #
FEATURE(`accept_unresolvable_domains')dnl
dnl #
dnl FEATURE(`relay_based_on_MX')dnl
dnl #
dnl # Also accept email sent to "localhost.localdomain" as local email.
dnl #
LOCAL_DOMAIN(`localhost.localdomain')dnl
dnl #
##########

The main point here are the ones to "accept_unresolvable_domains", LOCAL_DOMAIN(`localhost.localdomain').

see if this is the same.  if you have configured sendmail not to accept for these then there might be a problem. when you try from the command prompt or the telnet 25 option, the server uses the local list of people available first and then for any internet names resolves it from the DNS and therefore never gives you a problem.