title: Outlook 365 Selection Event
body: <p>Is it possible to create an Outlook 365 add-in that monitors when the user selects an e-mail message and performs actions on the selected e-mail message?  (I need to develop a custom add-in that, for example, displays notification when the user selects an e-mail message that contains external links and removes these external links from the e-mail message.)  If it is possible, could you please tell me which technologies (Outlook Rest API? Outlook Web Add-in? Microsoft Flow custom action?) I can use to implement this functionality?  (I can easily implement this functionality, using VSTO, for desktop Outlook, but I am new to Office 365 development.)  Thank you.</p>