[Exim] OPEN_RELAY PROBLEM

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Hi,

We are using Exim 3.22 as MTA in our Nursing School, and we want that
our mail server make relay from outside clientes with the condition that those clients are
local users.

At this moment it works like this, but we were notified that our server
acts as open-relay server and we don't know how to resolve that
situation. In an other way, we have a little idea how to solve it, but
after a few experiments the problem remain.

Thanks.

PS: Sorry for the bad english.
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