I have a gateway / mailserver running Red Hat 9, and 2 client pcs (Slackware 9, and Windows 2000).
I can receive email on both client pcs by running ipop3 on the server, now how do i send email?
Sendmail is installed on the server in its default configuration.

Can anyone help?

Make sure that SMTP is running correctly. FIrst test is to telnet to the mailserver to port 25. The command is
telnet serverIP 25
What does it print? Can you connect?

i can connect using telnet from the client pc but when i try and send an email from Kmail it says something like "621 can not relay" (thats from memory, i'm at work now)

There is some configuration that must be done with Sendmail if you are going to use it for a mail server. Look at the file sendmail.mc located in /etc/mail. Follow the guidelines in the file and make changes as necessary. Mostly you would need your mail domain name(i.e.: mail.server.com) whether or not you will be relaying through another mail server (from your isp) and some other data you might need (your public ip address). Since you are using RH9 you will probably have to use the m4 engine to convert your sendmail.mc file into the sendmail.cf file. Look at one of the man pages to walk you through the proper syntax. It is just a one line code but I always have to look it up. Then just make sure that sendmail is running. Do a ps aux |grep sendmail and look for it to be running. If it isn't start it. Come to think of it, you'll have to resart it once you compile the new sendmail.cf file.

Still having problems here...

I have set up Sendmail as my outgoing account in Kmail and i can send an email but then later i get this message in local mail:

The original message was received at Mon, 8 Mar 2004 07:50:28 +1100
from localhost [[UNIX: localhost]]

----- The following addresses had permanent fatal errors -----
<user@example.com>

----- Transcript of session follows -----
451<example.com>: Name server timeout
Message could not be delivered for 5 days
Message will be deleted from queue

Well, there are actually quite a few things that can cause such problems.

1) Is sendmail up and running and listening? Check by doing "ps -ef | grep sendmail" Look for one saying that sendmail is in fact listening.

2) Do the MX records actually point to your email server? If not check with your isp and make sure they are.

3) Do you have all the clients who you want to have email accounts actually have accounts on the server? They will have to before it will work.

4) Have you gone through the /etc/aliases file and registered all of the aliases for the authorized user? Look at the examples to see the proper sysntax. After making any changes you will have to run "newaliases" from a command prompt to validate the new file. No parenthesis necessary.

Try looking at these things and then reposting.

Thanks for the reply...

1. Yes, Sendmail is running

2. I only have an MX record for my local mail server not my ISP's mail server, is this the problem?

3. Yes

4. I havent set up any aliases, do i have to alias my ISP email to my local network name?

Sorry I didn't get back to you. I have been out of town at a cyber security seminar. It would appear that everything is like it is supposed to be. One question I do have is are you in fact using this machine as a mail server available out on the internet at a public ip address? If so, then all your isp needs to do is make sure that their MX records point to your server. That way all the mail that will come through them gets routed to your server. As far as your aliases, the aliases are just for the users/clients on your server. You might have a user called Billy Bob. In the aliases file you might have all of his aliases listed: billy.bob@mailserver.com, billybob@mail.server.com, etc... it is often used for sending mail to one person that might come in addressed to different people. For example, the mail that is sent to postmaster will usually get forwarded to root. This is done in the aliases file. You would also have to enter yourself in the aliases file as all mail going to root should be forwarded to you.

After looking at the message again and finding this info out, it might be that your machine can't get to a DNS server to resolve the email. Do you have all of that kind of info entered correctly in your eth0 config? Check it out and repost.