restrict relay of a relay on a machine by machine basis

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restrict relay of a relay on a machine by machi...
\ Thomas Bolioli (20 Dec 2007)
. \ Miguel Da Silva - Centro de Mate (20 Dec 2007)
. . \ Thomas Bolioli (20 Dec 2007)
. . . \ Noel Jones (20 Dec 2007)
. . . . \ Thomas Bolioli (20 Dec 2007)

Subject:	restrict relay of a relay on a machine by machine basis
Group:	Postfix-users
From:	Thomas Bolioli
Date:	20 Dec 2007

I have a buddy I allow to relay through me but someone he allows relay
for I need to shut off. How can I do that?
In other words, clients a, b, c, & x relay through intermediate y, then
y through exit point z. I want to continue to allow y to relay but only
for clients a, b & c, and shut down z. Is that possible?
Thanks,
Tom