Smtp.NET

Professional Email Component for ASP.NET and .NET Windows Forms which doesn’t extend the System.Web.Mail namespace but was built from the ground up to go further and offer you more. Smtp.NET was designed to be the easiest .NET email component to learn and use, unlike competitors that require you to learn their object model simply to send an email.
Features HTML Email with automatic image embedding, authentication, automatic ZIP compression of attachments, support for message queuing on IIS & emailQ.NET, mail merge, multiple attachments, multiple recipients, specify multiple servers for failover and redundancy, and more. Smtp.NET is installed in the GAC (Global Assembly Cache) for easy access by all of your developers. Smtp.NET is feature rich and offers functionality that the System.Web.Mail.SmtpMail class cannot.
Fully supported and documented with extensive examples to jump-start your application development.
Royalty-free redistribution licenses, site-wide licenses, and multiple user discounts are available.