Unfortunately there is not a built in option to be able to change the number of maximum users that can participate in a private message. If a user does not wish to receive updates, they are able to Hide new Activity:
However your team might consider creating a discussion with Specific People, instead of using a private message. This would allow you to limit the people on the thread, it would also allow you to have more tools/options with the the text editor.
Hope this helps.
Thanks for the comment John Decker. I'm aware of the "Hide new activity" feature and use it quite often; I thought there may be functionality built into Jive on the admin side, where I would be able to restrict the number of participants in private messages (similar to the settings that allow me to require users to be connected to send a private message to one another). 100 participants is quite excessive. Unfortunately your second bit of advice would prove to be rather difficult (my team consider a discussion with specific people), because our Jive Community is not used internally by employees but by our students.
Some of them use the messaging feature as a way to "IM" one another. What inevitably ends up happening however, is there will be several students that no longer wish to be on the thread. There is nothing preventing them from being added to the thread, and there is no way for those individuals to remove themselves from the thread. The bigger issue is the large number of emails that this amounts to. However, these users don't wish to turn off email notifications for private messages, because someone from Penn Foster may send them a message (myself, Instructors, etc.) and they want to be notified immediately.
Thanks again for your comment!
Thanks for the details Stacey.
Since there isn't a built in feature to limit number of participants within a message, you might consider creating an idea for a feature here Ideas for Jive. This would allow others to vote it up and help it gain visibility with our Products team.
There has recently been a new process implemented by our Products team to help review popular ideas. This document provides more details surrounding ideas and feature requests: Welcome to the New Ideas for Jive
Hope this helps.