Message Groups help you start to segment your customers subscription preferences. You might have a Message group for Sales, one for Offers, one for Technical News etc.
Message Groups can be defined in Organisation Settings -> Messenger and under the Message Groups option from the navigation menu on the left:
Click on Create Group to add a new Group and fill in the Name and optionally a Desciption:
Every Message in Fortifi can be assigned a Message Group on the Settings page:
By Assigning a Message to a group, if the recipient follows an unsubscribe link on that Message, they will be Unsubscribed just from that group. This allows you to unsubscribe users from Sales but keep them subscribed to Tech News for instance.
There is still an Unsubscribe All link you can add to your Messages which will unsubscribe the user from All message groups: