[Mailman-Users] Disable / Enable Mailinglist

[David J. Barrus]

Is there a way to disable the mailinglist after my client sends out an e-mail and then re-enable it when they want to send out another one?

Here's the problem:
After my client sends out an e-mail through their mailinglist, occasionally one or two recipients reply to it and their message goes out to everyone on the list.  Maybe I need to change something in the General Options.  Any help would be greatly appreciated!

Thank you,
David