Creating Add-in
We can create an Add-in either by using Yeoman Generator or Visual Studio. The Yeoman Generator creates a Node.js application that is managed with code editors like Visual Studio Code, Atom, Sublime Text, etc.
Here we will learn how to make an add-in using Visual Studio step by step.
First, we have to install Visual Studio with the Office development workload or SharePoint development workload installed.
Now, Open the Visual Studio Menu bar and follow the below steps:
File -> New -> Project
In the project list, select Outlook Web Add-in which is situated under the Visual C# or VB (Visual Basic) under the expanded Office/SharePoint submenu.
Name the project and finish the setup.
Visual Studio will create a solution and its two projects will appear in Solution Explorer. The file MessageRead.html will open in Visual Studio.