Continuo ad indagare e secondo me sta qua il problema:
[root@mail /]# rpm -qa | grep spamassassin
warning: only V3 signatures can be verified, skipping V4 signature
warning: only V3 signatures can be verified, skipping V4 signature
smeserver-spamassassin-2.0.0-3.el4.sme
warning: only V3 signatures can be verified, skipping V4 signature
warning: only V3 signatures can be verified, skipping V4 signature
spamassassin-3.3.1-52.el4
Ho due versioni di spamassassin installate ?!?