In many situations (normally in buisness correspondance), an email discussion with the client needs to include many people from both sides. As long as everyone keeps replying to each other, its no big deal – the first person went to the trouble of adding all the required people and everyone else just “Reply All” eveytime.
This gets a little more complicated when you have something new to say which should belong on the same thread of an already active discussion, but still need to be delivered to the same people. You now have the option of either composing a completely new email and adding all those people by hand, or using “Reply All” and removing manually all the content of the old discussion before starting a new one. The problem with the latter method is that it does not remove headers that the email software would send on this particular eventulity, which include items to allow advanced mail user agents to understand context of discussions – who replied to who and when. Such email clients will display your new message as part of the original thread.
Kmail/Kontact offers a simple way to solve this problem: creating distribution lists is as easy as locating an email item containing all the people you want in your new list. Now just hit “Replay All” on that email and click “Save as list”. Type in a new name for that list and “Ok”. Now you can close the original email, and start a new clean composer in whose address bar you can start typing the name you just gave your new distribution list. The mail compose will of course help you by auto completion.