As you may already know the Email notification preferences can be set by the user by going to preferences/Change email notification preferences and here the preferences can be set for each approvable.
When you make changes globally it is either all/none, you cannot make changes at the Global level that will change notification preferences for individual users. Please log a service request with more detailed information on what kind of emails the users want to avoid and we will look into it and see if there is some way to stop these notifications.
Do you know which email notification preference controls the following email. The users would like to eliminate it.
Subject: PCCR4894 - Reconcilation for order PC14264
PCCR4894 - Reconcilation for order PC14264 has been modified by Jack Lawrence
I tried an number of 'Purchase Reconciliation; settings but nothing has worked to date.
'Purchase Reconciliation should actually work for PCCRs, you can turn on notification/debug to get more info in the logs. Can you log a Service Request with us and send us the logs.