Sendmail and SMTP AUTH on RedHat Linux 9
Part 4 - Testing Sendmail

Written by Tony Bhimani
December 5, 2004

Requirements
RedHat Linux 9
Sendmail 8.12.8
Cyrus SASL 2.1.10

Our last part of the adventure is testing Sendmail. I'll be sending an email from Outlook Express to one of my Hotmail accounts. If all goes well, then my reply to it should be accepted by Sendmail and stored in the webmaster mailbox.

You don't have to use Outlook Express, but the client you do use should be able to handle SMTP authentication. First thing you need to do is create a new account in your mail client. I won't be showing the steps for this, so consult your client's documentation if you get stuck. Use the DNS name (i.e. mail.yourdomain.com or whatever you set it up as) of your mail server for the SMTP and POP3 servers. The username should be the Linux system account name you created and use the password you assigned it.

Create a new email message and make sure it is being sent from your Sendmail server. If you have a Hotmail or Yahoo account, you can send the message there.

When you are done composing your message, try sending it out. You should get an error, 550 relaying denied, showing that SMTP AUTH is doing its job. All mail sent from your server needs to be authenticated by a valid login and password.

The following steps are meant for Outlook Express, so if you are using a different client then check the documentation where SMTP authentication can be enabled. In Outlook Express go to the Tools menu and select Accounts. Open the Properties to your mail account and select the Servers tab. At the bottom of the Servers tab, there is a checkbox called "My server requires authentication." Put a check on it and select Settings.

When the Outgoing Mail Server dialog box comes up, make sure the first option is selected. Click OK.

Click OK on the property window. You should now be back at the Internet Accounts window. Click Close.Try resending your message. This time it should send without any errors.

Check and see if you received your message. I sent mine to my Hotmail account and received it successfully.

Obviously sending outbound mail works, but now we need to check if Sendmail will receive mail. Reply to your message.

After your message is sent, go back to your Sendmail server. Switch to the /var/spool/mail directory and do a listing (ls -la). If your message was received then the mailbox size should not be zero bytes.

cd /var/spool/mail
ls -la

Let's check the webmaster mailbox contents. Issue the following command.

more webmaster

Our Sendmail server is working properly. All we need now is a POP3 server to fetch mail with our client. Configuring Qpopper for POP3 access is covered in this tutorial.

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