Block All external contacts except some domains in Skype for Business.Block some External domain contacts in Skype for Business.Block All External Contacts in Skype for Business:.We can apply the block the external contacts in following ways, It’s a simple setting in Office 365 performing this function. Most of the organizations, have blocked the users to contact other organization people due to some protocol with in their company.ĭo you want to know, how the Office365 administrator blocking the external contacts.