I wrote very simple code to send emails. I wish that end users who do not have .NET Framework installed, could also install this application without installing .NET Framework. I
The .NET Framework is required on your client machines, even for a single line of .NET code.
This applies only to client code; ASP.NET, which runs on a separate machine and serves up HTML, does not require the .NET Framework on the consuming PC.
You might be interested in the .NET client profile. Applications written against this .NET framework subset require a much smaller install (approximately 28 MB) than that required by standard .NET applications.
If you are developing a web application then .NET Framework required only on the server where you host the application, not for client machines.
But for a desktop application .NET Framework is an essential requirement for every machine where you use your application even if it has only a single line of code.