asp.net - 電子メールはasp.netに実際に存在し、このエラーを表示します

Question

System.FormatException: The specified string is not in the form required 
                        for an e-mail address.
at System.Net.Mime.MailBnfHelper.ReadMailAddress(String data, Int32& offset, 
                                                String& displayName) at 
 System.Net.Mime.MailBnfHelper.ReadMailAddress(String data, Int32& offset) at 
 System.Net.Mail.MailAddressCollection.ParseValue(String addresses) at 
 System.Net.Mail.MailAddressCollection.Add(String addresses) 
 at MasterPage.btnJoin_Click(Object sender, EventArgs e) in 
 d:\Visual Studio 2010\SocielNetwork\MasterPage.master.cs:line 25