PMDF System Manager's Guide

VMS MAIL and PMDF must cooperate closely in their handling of errors detected during message interchange. PMDF is careful to inform VMS MAIL about any errors it detects while VMS MAIL is sending a message to PMDF. Conversely, PMDF tries to handle the various error conditions that can arise while delivering a message to VMS MAIL.

PMDF categorizes errors returned by VMS MAIL as either temporary or permanent. A temporary error is something like "node down". Such a problem might be corrected in the future. A permanent error is one like "no such user" which is unlikely to be rectified in the future. PMDF treats the following errors as permanent errors:

NOSUCHNODE --- Specified DECnet node does not exist
NOSUCHUSR --- No such user exists
USERDSABL --- Specified user cannot receive new mail
SYNTAX --- Syntax error in username/node specification
TEXT --- Error occurred during MAIL-11 message delivery.

In the case of a temporary error PMDF simply aborts its attempt to send the current message. Periodic attempts will be made to send the message until the error condition disappears and the message makes it through. (Note that if the error condition is never remedied the message will eventually "expire" and will automatically be returned to the sender.)

In the case of a permanent error, PMDF records both the bogus address and the error it generated. PMDF then dispatches a notification of the error, along with a copy of the message, to the sender. An additional copy of the error notice is mailed to the local postmaster (usually, but not always, the system manager) by default. The sending of failed mail notices to the local postmaster can be disabled by adding the nosendpost keyword to the local channel block in the PMDF configuration file. Return of message contents to the postmaster can be restricted by adding the postheadonly keyword to the local channel.