In ASP.NET 2.0, Microsoft deprecated the System.Web.Mail namespace and replaced it with System.Net.Mail. The new library introduces some new features, but it also includes some bugs in how mail is sent. Before discussing some of these in detail, let's go through some code sample (which assumes you've added a using System.Net.Mail at the top of the file):

MailMessage msg = new MailMessage();
msg.From = new MailAddress("address@domain.com", "Person's Name");
msg.To.Add(new MailAddress("destination@domain.com", "Addressee's Name");
msg.To.Add(new MailAddress("destination2@domain.com", "Addressee 2's Name");
msg.Subject = "Message Subject";
msg.Body = "Mail body content";
msg.IsBodyHtml = true;
msg.Priority = MailPriority.High;
SmtpClient c = new SmtpClient("mailserver.domain.com");
c.Send(msg);

The code is similar with some minor changes to how you address the message. Instead of constructing an address, you can let the system do that for you. If you specify an e-mail address and a name, it will automatically display in the message as this:

"Person's Name" <destination@domain.com>

This is the "proper" form for an e-mail address. You can add multiple addresses to the To, CC, and BCC collections in the same way as shown above. This is programmatically easier to do than sending lots of messages—just add multiple addresses to the BCC property in order to send a mass mailing.

As previously mentioned, this new namespace has a couple of bugs. The first is when you send a message the headers are all added in lowercase letters. While the RFC for SMTP mail doesn't specify how the headers should be capitalized, many spam filters restrict messages where the headers are not properly capitalized.

The other bug deals with the Priority setting, which should mark a message as important within the mail client. Because of the way the header is formatted, my mail program (Eudora) doesn't recognize it as the priority flag and doesn't mark the message as important. While this seems trivial, it's a change from the System.Web.Mail version for no apparent reason. I'm continuing to research this and if I can't find a good fix, I may switch back to System.Web.Mail and deal with the warning messages that Visual Studio displays about System.Web.Mail being deprecated.