At 12:00 PM 10/5/2001, Jacob Palme wrote:
I do not think IETF has any standard for loop control in e-mail,
except the priority value in MX records.
mx priorities do not provide loop control
Common methods for loop control:
(1) Trace list on the message. We have this, in the
"Received:" header, but no spec how it should be used for
loop control. This is not as easy as it can seem, since a
message can legitimately come and go several times to the
same MTA, for example after mailing list expansion.
Your "this is not as easy" sentence is extremely important.
(2) Store, in the MTA, the Message-IDs of messages passing.
here, to, the problem is that the message can legitimately transit the same
site more than one time.
My own sense is that counting the number of Received headers citing the
local system's domain name, and then bouncing messages that have more than
N such headers. Offhand, 3 seems safe, though 4 is probably just as
effective and more safe.
d/
----------
Dave Crocker <mailto:dcrocker(_at_)brandenburg(_dot_)com>
Brandenburg InternetWorking <http://www.brandenburg.com>
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