Generating HTML email body in C#

You can use the MailDefinition class.

This is how you use it:

MailDefinition md = new MailDefinition();
md.From = "test@domain.example";
md.IsBodyHtml = true;
md.Subject = "Test of MailDefinition";

ListDictionary replacements = new ListDictionary();
replacements.Add("{name}", "Martin");
replacements.Add("{country}", "Denmark");

string body = "<div>Hello {name} You're from {country}.</div>";

MailMessage msg = md.CreateMailMessage("you@anywhere.example", replacements, body, new System.Web.UI.Control());

Also, I’ve written a blog post on how to generate HTML e-mail body in C# using templates using the MailDefinition class.