[EXIM] Detecting the return code of procmail?

We've got things set up so that final delivery is done via procmail if a
.procmailrc exists in a user's home directory. However if that user is
over quota mail sent to them bounces as undeliverable instead of being
queued for a future deliver attempt with an error message that looks like:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to all of its recipients.
The following address(es) failed:

  user@???:        
    (generated from user@???):
    Child process of procmail_pipe transport returned 73 from command:  
    /usr/local/bin/procmail

The error code in this case is always 73.

Here's what the procmail_pipe transport is set to:

# delivery by procmail, local users with .procmailrc files only
procmail_pipe:
driver = pipe
command = "/usr/local/bin/procmail"
from_hack
user = ${local_part}

And the driver:

# Use procmail only if a ~/.procmailrc file exists, and procmail exists.
procmail:
driver = localuser
require_files = ${local_part}:${home}/.procmailrc:+/usr/local/bin/procmail
transport = procmail_pipe

Ideally I'd like to be able to change things such that if procmail returns
error code 73, the mail would be defered instead of bounced.

Any ideas on how this might be accomplished?

TIA,

Tabor

-- 
________________________________________________________________________
Tabor J. Wells                                          twells@???
Shore.Net Systems Admin.     Just another victim of the ambient morality

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