The logic for checking entries in the profile database (UNIX only), pipe database and pipe channel option file is as follows:
user@host entry.
user@host
entry.
user@host entry.
host entry.
host entry.
If no profile database entry exists (as is always the case on OpenVMS)
and if the pipe database does not exist, then only the pipe option file
is checked, i.e., steps (3) and (5) only. If no profile
database entry exists (as is always the case on OpenVMS) and if the
database file exists but cannot be opened, then the message is passed
over --- the condition is treated as a temporary error. And when checks
(1)--(5) turn up no results, the message is bounced.