If you want to save data by posting a form using ASP.NET MVC, all data is always validated so that potentially dangerous content is blocked.  But sometimes you want to let your users post HTML to the server, for example with a text editor (wysiwyg). 

You can allow this for a specific function withing your ASP.NET MVC Controller.  Just use this function attribute in your controller:

<ValidateInput(False)> _