System 2.0.0.0 4.0.0.0 System.Enum Use the enumeration as a parameter to the property to specify the delivery method. Specifies how email messages are delivered. Field 2.0.0.0 4.0.0.0 System.Net.Mail.SmtpDeliveryMethod Email is sent through the network to an SMTP server. Field 2.0.0.0 4.0.0.0 System.Net.Mail.SmtpDeliveryMethod Email is copied to the pickup directory used by a local Internet Information Services (IIS) for delivery. Field 2.0.0.0 4.0.0.0 System.Net.Mail.SmtpDeliveryMethod Email is copied to the directory specified by the property for delivery by an external application.