In a “one armed installation” using a single listener, how would the system differentiate
between incoming and outgoing email?

A.
Mail flow direction is determined by the “Recipient to” field in the SMTP envelope.

B.
Mail flow direction is determined by the type of listener, public verses private.

C.
Mail flow direction is determined by using the source IP address.

D.
Mail flow direction is determined by the “Mail From” field in the SMTP envelope.