To simply answer your question yes, yes it can, with very little configuration work necessary:
For the Director & PA to receive a copy of all incoming e-mails:
User properties of the directors account exchange general tab (Fordwarding address, deliver messages to both
forwarding address and mailbox.
PA to send messages from the director = PA’s outlook client enable the “from” field then from a computer that has active directory users and computers (ADUC), open ADUC select View -> Advanced Features, find the directors user account and display the properties, select the security tab add the user/group (the PA) and give the PA “send as” permissions, OK out of everything wait a while (a couple hours for the permissions to apply MS KB327378) the PA will then be able to fill in the from field in a new message to “send as” the directory.