<FORM ACTION="/cgi-bin/maillist" METHOD=post>
  <INPUT TYPE=hidden NAME="list" VALUE="cyberads">
  <STRONG>Enter your e-mail address here to receive updates.</STRONG>
  <INPUT TYPE=text NAME="email" SIZE=30>
  <INPUT TYPE=submit VALUE="Keep me updated!">
</FORM>
      
The important thing to notice is the value of the input list. Because this is how the mail filters recognizes what to process. You can change the value from cyberads to any other name you wish. Also be sure to change the ACTION to the appropriate CGI script. 
 
The CGI script that we wrote was written in perl. The most important thing about the script is that it sends the mail with the subject line as: subscribe cyberads. The information will change depending on what you put as the value in the HTML code above. This subject line is what your mail software use to distinguish between this kind of subscribe message and your other email. 
 
When you or the person in charge of the mailing list receives the mail, your mail software will begin the process of handling the subscribe message. But first you have to set it up so it knows what to do. We'll use Pegasus Mail version 2.42 as an example, but Eudora Pro, BeyondMail and other mail software also have similar configuration steps. 
 
Pegasus Mail and mail-filter rules

Pegasus Mail, like other mail software, has mail-filtering rules to sort your mail. We use these filter rules to accomplish three steps: 
1. Automatically send a message to the user acknowledging their subscription 
2. Place the user on a mailing list 
3. Move the subscribe message to a storage folder once you have had a chance to look at it. 
 
We use the mail filter to setup a rule for each of these steps. First, create a mailing list (it's called distribution list in Pegasus). You can find it in the Addresses menu or by pressing F6. 
 
Click New List, enter the name of the list, and click OK. 
 
Next, you have to create a mail folder where these subscribe messages can be stored. Go to your mail folders window (Ctrl-L or File | Mail Folders) and create a new mail folder. 
 
Third, create a file with the text that you want to automatically send to the user. Things that you can write include a little introduction about the list, how many times a month the newsletter is sent, and information about how to unsubscribe (we'll get to that later). 
 
This is also a good time to create a file for when the user decides unsubscribe from your newsletter. 
 
Creating the mail-filter rules
 
Once you have finished the above steps, then you can create the mail filter rules. Go to the File menu and select Mail filtering rules | edit new mail filtering rules | rules applied when folder is opened. Alternatively, you can click on the button that has a red funnel and a blue arrow pointing down. 
 
To create the first rule of automatic replying to the user, click on Add Rule, and click on In these headers and Subject:. This tells the Pegasus to look for the trigger text only in the Subject header of the mail message. What's the trigger text? It's the text that identifies the email as a subscribe message, and in our case, it's subscribe cyberads. So we enter subscribe cyberads  into the Trigger text field. 
 
Now that we have established the rule for picking which message to act upon, we need an action. In our case, they are the 3 steps that we want accomplished. So first we'll use the action to send an automatic reply to the user. Choose Send text file in the Action to take field, and a dialog box will pop up asking you for the location of the file. Choose the file that you created earlier, and click OK. That's it, the first rule is completely done! 
 
The other two rules are similar, except for the action to take. For adding the user to a mailing list choose the Add user to list option and for moving the message into a mail folder use the Move option. 
 
Unsubscribe is important too!
 
You also have to have a mechanism for users who may want to unsubscribe from your newsletter. You should include in the automatic reply a line or two about unsubscribing. Our procedure is to reply with a unsubscribe Cyberads in the message. Unsubscribing involves the same steps as subscribing, except for the reverse actions that need to be acted upon. 
 
Once you're finished with the whole setup, it would be prudent to check it first by subscribing your own email address as a test. Go through the whole subscribe and unsubscribe procedure and make sure that each step has been executed correctly. 
 
For more information check out these sites: 
Pegasus Mail - http://www.pegasus.usa.com/  
Eudora Pro - http://www.eudora.com/