How is the default eMail address in the eMail Subsystem Configuration page used?

A.
It receives all mail sent in the Send eMail step as a bcc.

B.
It is the From address for emails sent by agents using Agent E-mail.

C.
It is used if no email contact is specified in the Create eMail step.

D.
It becomes the From address in the Send eMail step if no address is specified.

Explanation: