Specifies the authentication mechanism to use when authentication is required to send messages to an SMTP service using a TCP/IP network socket.
The CdoProtocolsAuthenticationenumeration is provided for this field.
If no value is set for this field, anonymous (no authentication) is assumed.
This field is used only if the sendusing field is set to cdoSendUsingPort (2). These settings mean that messages are to be sent or posted over the network.