[comp.os.vms] MAIL idiosyncrasy with sequential files

VORBRUEG@DBNPIB5.BITNET (08/20/87)

I just discovered that MAIL still supports the old sequential files
from version 3 of VMS. This gives you the possibility to nicely include
any text in you mail file; I just used this to 'digest' some old
digest files from info-vax, clear out all that header rubbish, etc.
That's the feature, and a good and very necessary one.

Now, MAIL has some very strict rules as to what it will accept in this
format: It will only parse the header (To:, From:, and Subj: fields)
if they are precisely in that form (followed by a <TAB>), and preceeded
by a form feed. OK, why not...but it forgets to put in a form feed at
the beginning of a file if you extract your mail. And that's a nuisance!

I admit it's only a very small bug, but it had me baffled for some
time...I just didn't expect that sort of inconsistent behaviour...there,
how you can get spoiled! :-)


   Jan Vorbrueggen

leichter@VENUS.YCC.YALE.EDU ("Jerry Leichter") (08/20/87)

	I just discovered that MAIL still supports the old sequential files
	from version 3 of VMS. This gives you the possibility to nicely
	include any text in you mail file; I just used this to 'digest' some
	old digest files from info-vax....

	Now, MAIL has some very strict rules as to what it will accept in this
	format: It will only parse the header (To:, From:, and Subj: fields)
	if they are precisely in that form (followed by a <TAB>), and
	preceeded by a form feed.

Actually, a mail header must be preceeded by <FF><NUL>.  (This is a security
mechanism, added in something like V3.4 to prevent "spoofing":  Before that,
you could send someone a message that contained a formfeed followed by a
valid- looking header and MAIL would decide it was a separate message - which
you could make be "from" anyone.  Since MAIL discarded <NUL>'s when reading
its input, you could no longer fake it out.  Since these days mail files
receiving new mail messages are only rarely sequential, and not amenable to
this form of spoofing, so of the old error checks may no longer be there.  In
particular, I suspect that MAIL these days will send large files in block
mode, and then not remove NUL's.

				  OK, why not...but it forgets to put in a
	form feed at the beginning of a file if you extract your mail. And
	that's a nuisance!

It didn't forget anything; YOU forgot the /MAIL qualifier on your EXTRACT
command!
							-- Jerry
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