If two users belong to roles which are linked, then they can communicate with each other via PiSuite inside your web site.
Following is a screenshot of the page in PiSuite where you can maintain the linked roles. The role membership for a user is passed from your web site to PiSuite as part of the user identification JSON string created by your web site.
If your users are authenticated, then you can create a role in your web site e.g. named "SupportTeam" and can assign users to that role. The role assignments for each user are communicated to PiSuite every time a user vists your web site.
Then in the PiSuite administration site, you need to link the role "SupportTeam" with the roles that you want to enable to exchange messages with the support team.
If your web site uses anonymous users, then you need to manually create users in PiSuite for the Support team.
Click on the icon 
to send messages to the support team or to the contact person responsible for this demo site.