Often times you may want to render a custom validation message that contains HTML markup.  If you simply add the line:

@Html.ValidationSummary()

This will encode the markup so that less than signs and greater than signs are rendered < and >, respectively.  This, of course, is not what you want.

To render your HTML markup, its a little dirty, but it does work.

Simply add the following to your view:

@Html.Raw(HttpUtility.HtmlDecode(Html.ValidationMessageFor(m => m.Email).ToHtmlString()))

Where “Email” is a property of your model.