It looks like you go into each group you belong to, and look under Group Menu to find Alerts. This takes you to ...
Alert Settings
Use the options below to customize when you receive alerts for this group.
TEAM MATCHES: new team match begins
VOTE CHESS: new team vote chess match begins
NOTES: a new post is made to the Group Notes
NEWS: news item is posted to the group
FORUMS: new forum topic is created
PHOTOS: a new photo album is posted
EVENTS: a new event is posted
and you can untick the ones you don't want. (By default, they are ALL ticked.)
I don't mind being in a group but I don't want to be bothered by every little tidbit someone thinks needs to be posted. How do I block activity messages? I looked it up in help and it says controlled by group now .. I don't see HOW it is controlled ..