[Exim] Exim Testing - How to make local test messages appear…

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Before I open up port 25 to the "big ugly world", I would like to do a few
tests of routers ..etc with email that appears to be from the outside.

I've tried -f for sender and -oMa -oMs for remote IP/name but Exim always
appears to show local sender.

Any options I can use to do this ?

Leigh
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