An alternative if you are in a Hosted plans that does not support the plugin linked.
You could also use a Group Mailbox. As this is for Support I would create create a Seperate group and add moderators and other elevated users who mig get help with these processes. If needed you could also create say 2 Groups. One for verification and one for support. The Ppl messaging don’t need to be part of the group. Just have to have group visible and able to be messages by everyone.
Then add link(s) to where you want this to be visible for members to create the group mailbox pm.