Requirement
My client has multiple Business Units and all BUs need Read Only access to ALL accounts but these BUs are competitive in nature and they should not be able to view each other activities. I understand if they have access to account they can see all activities but I want to restrict the visibility of all activites tasks, events and emails based on the BUs.
I can only create 2 restriction rules per object, therefore, can't use all the BUs to restrict activities. Also can I restrict visibility of emails using restrictions rules?
What other solutions I can provide my client to meet this requirement?
A quick correction to what was mentioned above for future readers:
OWD "private" for Activities does in fact NOT hide them from everyone but the owner (and role hierarchy). See documentation for "private" on Activities: "Only the activity owner, and users above the activity owner in the role hierarchy, can edit and delete the activity; users with read access to the record to which the activity is associated can view and report on the activity."
Which means, if the Account was shared with multiple BUs they would see each others Activities, too.