The ServerPort property returns the port number that was
used to establish a connection with the mail server. Setting this
property specifies an alternate port number to use for a subsequent
connection. A value of zero specifies that the default port should be
used for the connection.
The mail server must support Post Office Protocol v3 (POP3) to
retrieve messages. Setting this property does not affect what server
is used to deliver messages. See the RelayServer and
RelayPort properties to specify a mail server that is
responsible for relaying messages.