Proper netiquette dictates that when on a Mail List or replying to News Groups one should never use HTML or rich text formatted messages. The question then becomes "How do I set up Outlook Express to accomplish this ?". From the "Tools" menu choose "Options"
You should then see something like this
Make sure that "Include message in reply" is unchecked and that the Mail Sending Format is set to "Plain Text" Setting your Mail reader like this will insure that you will be a good List citizen. You may however wish to leave these settings unchanged so that your day to day mail goes out in HTML format and that when you reply to a message that the message you are replying to is included in the one you are sending. If this is the case there are still things you can do to reply properly to a List.
First hit reply as usual. Then form the reply-compose window choose "Format" and select "Plain Text"
Once this is done you need to look carefully at the replied to message that was included. Try to include only that part of the message that is absolutely necessary to keep the continuity of the conversation. In most cases this is just a few lines. If you read the list in "Digest" mode you will find that the entire digest is included in your reply and if you do not take the time to delete it it can cause the list to become hopelessly clogged and unreadable. It may even result in your suspension from the list. One of the easiest ways to delete the unwanted text is to select "Edit" then "Select All". Once the text is highlighted you can then hit the delete key or simply start typing your message and it will go away
If on the other hand you want to keep a portion of the original message use your mouse, click and hold the left button at the start of the text to eliminate then drag the arrow to the end of the unwanted text. This will highlight it and allow you to delete it as before. Selecting text in this manor takes a little practice but when mastered become very useful as the same technique works in almost all windows based programs. The one thing to remember is that the selection is not made until you release the left mouse button so if you accidentally select too much but have not released the button you can simply continue to move the mouse until the desired text is selected.
If you do not use Outlook Express for your mail reader don't despair. Most programs will have similar settings to make these tip work. It will just take a little exploring to find them. In the end you will find that you are better able to use your system as well as being a better list citizen.