The mode to use to authentication with the SMTP server
CAUTION Authentication is only available on the MS .NET 1.1 runtime.
Valid Authentication mode values are: None, Basic, and Ntlm. The default value is None. When using Basic you must specify the Username and Password to use to authenticate. When using Ntlm the Windows credentials for the current thread, if impersonating, or the process will be used to authenticate.
SmtpAppender Class | log4net.Appender Namespace