You cannot prevent someone from using the "Reply All" feature when addressing a distribution list. However, the following options may help:

• Use Bcc when emailing the list. This method can prevent "Reply All" situations where members of the list end up emailing everyone on the list not realizing who all will receive it.
• Rename the distribution list to make it more clear who the receipents are or what the purpose of the list may be.
• Rename the distribution list to make the name more cryptic, which can reduce the number of people who find it in a directory and use it.

Under extraordinary circumstances, depending on the need, the owner may be able to modify permissions of the distribution list to limit who can send emails to it.