System.Net.MailMessage allows some invalid email address formats
As many people may already be aware, correctly validating email addresses can be somewhat of a nightmare. You can search all day long for a C# regex that matches the current RFC standards, and you'll find different regex expressions that give different results. If you look at http://en.wikipedia.org/wiki/Email_address#Local_part , you'll see that a period at the beginning or end of the local part is not allowed. Two consecutive periods are also not allowed. However, the following NUnit test proves that System.Net.MailMessage allows you to instantiate a MailMessage object for some invalid email