These constant define if SSL encryption is used for the server, or for the relay that is connecting to 3rd party server. You should set wodSmtpServer.Security, and/or Relay.Security properties with these values. Setting these properties is independent of each other.

SecurityNone means that SSL cannot be used, and trying to use it will generate an error. This is default value, to preserve compatibility with older versions of wodSmtpServer.

SecurityAllowed will allow user to issue STARTTLS command to create secured connection, but is not required. In order to use this constant, Certificate property must be set with valid certificate.

SecurityRequired means that user must create secured connection using STARTTLS command before he tries to provide sender of the email using MAIL FROM command. In order to use this constant, Certificate property must be set with valid certificate.

SecurityImplicit will create internal SSL 'wrapper' over wodSmtpServer. Users that connect to the server will establish SSL connection prior to exchanging any data between the server and tehmselves. STARTTLS command is not used anymore because connection is already secured. Usually, servers using this type of SSL security are listening on port 465. In order to use this constant, Certificate property must be set with valid certificate.