I am using Microsoft Dynamics CRM 2015 on-premise version.
I created a custom entity(News). The use of this entity: the system administrator can share records(News) with selected System users.
My question: How to send Email Notification (to selected users) on Record Sharing?
Best How To :
There isn't any built in functionality to run a workflow on users who are selected in the record sharing form/window. If you wanted users to be able to run a workflow to send email for a particular record based on who it was shared to, you would need to have a CRM plugin written and/or a custom web resource built if you wanted this to be more of a manual process that is sent when a user says to run the workflow vs. the plugin which can be setup to run all the time when a record is shared to another user.
Below are a few links of with some example CRM plugin code that has been written to send email out to users for whom a record has been shared to them.