[Exim] Forged hostname

Hi all, we are seeing lots of spam with H=(our ip address) eg

H=(158.125.1.193) [210.114.196.215]

Spamassassin is catching most of them, but is there a good way to detect
and block this in an exim acl. I am sure somebody is doing it already
and it would save me reinventing the wheel.

Ron
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Ron McKeating
Senior IT Services Specialist
Internet Services and Software Solutions
Loughborough University
01509 222329