You can define mailing lists using aliases and alias files. This is handy and will work for small mailing lists with limited traffic (not too many new members getting in and out). With a growing mailing list, you will often get a few subscribers who have an improper email setup. Every time one member sends a message, he will get an administrative reply, stating that some unknown person did not receive email properly. This is annoying, as those members can't do anything to solve this problem.
Here is a trick. If you create a mailing list, say product-list, and then create another alias, owner-product-list, which points to yourself, sendmail will automatically send error messages to you instead of to the original author of the message.