SSLUseImplicit property (SMTP Connection Manager)
Specifies if implicit SSL mode should be used.
Use Implicit SSL
Use this property to specify, whether implicit or explicit SSL mode should be used. In explicit mode, the client connects to the generic FTP port (21), and then sends AUTH command. In implicit mode, the connection is performed to the dedicated port (usually 990), and immediately starts SSL negotiation (without sending AUTH command). By default, an explicit SSL mode is used.