This plugin adds a checkbox when composing a personal message that, when checked, will send the message to each recipient individually.
If you send a message to a group, each member of the group will be sent an individual message.
This is similar to using the BCC feature in email, where each recipient will receive their own copy of the email and will not be able to see replies from other users.
To use, enable the bcc enabled site setting.
The functionality is currently restricted to staff users.