Neither mailserver is NAT'ed. What could I have misconfigured?
Not sure.. dump a message through spamassassin -D and see how it's handling your Received: headers
Lines like these are relevant (this set illustrates the bug):
debug: received-header: parsed as [ ip=61.249.100.210 rdns=pp.kolumbus.fi helo=pp.kolumbus.fi by=xanadu.evi-inc.com ident= envfrom= intl=0 id=i66Ern95106902 ]
debug: looking up A records for 'xanadu.evi-inc.com'
debug: A records for 'xanadu.evi-inc.com': 192.168.50.2
debug: looking up A records for 'xanadu.evi-inc.com'
debug: A records for 'xanadu.evi-inc.com': 192.168.50.2
debug: received-header: 'by' xanadu.evi-inc.com has reserved IP 192.168.50.2
debug: received-header: 'by' xanadu.evi-inc.com has no public IPs
debug: received-header: relay 61.249.100.210 trusted? yes internal? no
debug: metadata: X-Spam-Relays-Trusted: [ ip=61.249.100.210 rdns=pp.kolumbus.fi helo=pp.kolumbus.fi by=xanadu.evi-inc.com ident= envfrom= in
tl=0 id=i66Ern95106902 ]
debug: metadata: X-Spam-Relays-Untrusted:
