In order to use DELIVER, you must first take two steps:

1. Create a MAIL.DELIVERY file in your default login directory. For security reasons this file must be located in your default login directory --- it cannot be stored elsewhere. The format of a MAIL.DELIVERY file is described in Section 5.2.¹
   This first step is all that is required to cause DELIVER to process mail delivered to you by PMDF. That is, the presence of a MAIL.DELIVERY file is all that is required to activate DELIVER for messages you receive via PMDF.
2. Set your mail forwarding address to "IN%""~username""" (OpenVMS 7.0 or earlier) or to IN%"~username" (OpenVMS 7.1 or later) where username is your username. See Section 1.1.7 for further information on using the SET FORWARD command.²
   This step is required to cause DELIVER to process mail you receive in your VMS MAIL mailbox by means other than PMDF.

Once these two steps have been taken, DELIVER will be invoked automatically to handle all mail as it is delivered to you. For example, suppose the user BOB on an OpenVMS 7.0 system wants to have DELIVER process his incoming messages. BOB should create a MAIL.DELIVERY file in his login directory and then set his forwarding address,

$ MAIL MAIL> SET FORWARD "IN%"" BOB""" MAIL> EXIT $