IT administrator of a global banking organization is responsible for configuring email services. The administrator must ensure secure communication between servers and clients. Which of the following statements about securing email protocols is true? $($Select the two best options.$)$

A$.$Simple Mail Transfer Protocol Secure $($SMTPS$)$ is the most widely implemented and robust method for securing SMTP communications.

B$.$Port $465$ is the recommended port for secure message submission over implicit transport layer security using STARTTLS command.

C$.$Post Office Protocol $3$S $($POP$3$S$)$ operates over transmission control protocol port $995$ by default for secured mailbox access.

D$.$Internet Message Access Protocol Secure allows multiple clients to connect to the same mailbox on port $143$ simultaneously.