Send chat notifications for group invites

I’m using the Mattermost integration for a group inbox, which is awesome as an additional notification channel and for behind-the-scenes chatter.

However, this is the inbox of a group that normally isn’t addressed directly, but instead invited to existing messages to handle them. This means that while replies are announced in Mattermost, initial messages are not.

Could we also have notifications for invites? :slight_smile: