From:	CSBVAX::MRGATE!@KL.SRI.Com:leichter@venus.ycc.yale.edu@SMTP 17-OCT-1987 13:28
To:	EVERHART
Subj:	re: DEC Mail Utility Madness

Received: from venus.ycc.yale.edu by KL.SRI.COM with TCP; Sat 17 Oct 87 09:46:53-PDT
Date: 17 Oct 87 11:43:00 EDT
From: "Jerry Leichter" <leichter@venus.ycc.yale.edu>
Subject: re: DEC Mail Utility Madness
To: "vms.macc.wisc.edu!dorl" <vms.macc.wisc.edu!dorl@unix.macc.wisc.edu>
cc: info-vax@kl.sri.com
Reply-To: "Jerry Leichter" <leichter@venus.ycc.yale.edu>

	We have several users who have choosen to use a different editor
	to compose their mail messages using the MAIL$EDIT logical name
	feature in DEC's Mail utility as explained in section 3.1 of the
	'Mail Utility Reference Manual'.

	This all worked fine until one of them tried to read a message
	with the READ/EDIT, NEXT/EDIT, FIRST/EDIT, or LAST/EDIT commands.
	Mail produces the following error messages when one has defined
	MAIL$EDIT and attempts to use these commands.

	 %MAIL-E-NOTCALEDT, this command procedure cannot be executed.
	         MAIL$EDIT does not specify a callable editor.

	Does anyone have any insight into this?  How would one define
	MAIL$EDIT so that the whatever/EDIT commands would work?

You cannot use a MAIL$EDIT value that causes a command procedure to be
executed with these commands - exactly as the error message says.  If you
want to use these commands, (a) your editor must support the standard callable
editor interface [see the documentation of callable TPU]; (b) your editor
must be INSTALL'ed (since it will be called, using LIB$FIND_IMAGE_SYMBOL, by
MAIL, which is a privileged program; (c) MAIL$EDIT must be defined to be
CALLABLE_your_editor.

				   WARNING

		Don't do around blindly installing alternate
		editors to make them work with this interface;
		they will run with MAIL's privileges, which are
		quite sufficient to do anything you like to the
		system.

							-- Jerry

(As to why this happens:  The commands that fail to work are those for which
the data to be edited may be in a temporary file with no directory entry
(LAST/EDIT), or not in its own file at all (the others - the message may
exists only as a couple of records in an ISAM mail file).  MAIL can provide
callbacks to itself across the callable editor interface, and thus provide
access to the data; for the "spawned editor" interface, all it can do is give
a file spec - which it doesn't have in these cases.)
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