Reply-to: for newsletters?
If you run a newsletter, it may be an issue for your users if they try to reply to the message, since the Reply-To: header of the emails are, by default, set to be list's posting address. This feature is designed for discussion lists, so that all replies go back to the list instead of just to the person who sent the original message, but it's obviously not ideal for newsletter-style lists. Instead, blank out the 'reply-to' variable in your list configuration. From then on, replies will go back to the sender.