I think by "transit operations" Dave means things like alias-forwarding and mailing list explosion.
Yea, as well as such scenarios as an organization that has MUAs, and an MSA, and posts all its mail through an ISP's MTA. The originating organization and the transit ISP are separate COGs.
d/ -- Dave Crocker Brandenburg InternetWorking <http://bbiw.net> _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf