But… stirring the pot can be a good thing, else the food sticks at the bottom of the pot and burns…
Mattermost is at its simplest, a team discussion and collaboration environment. There are the features of Mattermost:
Mattermost provides: 
    * group chat
    * direct messaging
    * private chat rooms
    * messages, comments and description fields 
      * a wide range of font formatting, headings, tables, and image embedding options
      * full markdown support
      * hashtags
      * Auto-highlight messages you wrote – to easily see what you said
    * file uploads - Share files and images internally and externally
    * archiving and search (including search by hashtag)
      * search public and private channels for historical messages and comments
      * view recent mentions of your name, username, nickname
    * support for  multilingual teams
    * comment threads for easy-to-follow conversations.
    * personalize notifications for unread messages and mentions by source
    * Access anywhere: clients available for computers and mobile devices - attach sound, video and image files from mobile device
    * email interaction (through Mattermail)
    * IRC bridge (does anyone still use IRC? I haven’t in ages…)
and also, in our particular case:
  * Eclipse project infrastructure for Mattermost (RSS, Git, Gerrit, Bugzilla, Eclipse Forums, Twitter, Mailing Lists, Jenkins/Hudson)
A lot of this can be done by email, but not everything.
I personally think it would be worth it to get off mail for this type of collaboration.