We seem to be having more problems than usual since we upgraded to 2.70. The latest involves Bayesian filtering. Incoming messages scoring higher than the spam threshold (we have set to 60%) get returned with the following message:
5.1.0 - Unknown address error 554-'Delivery failed: '
I am going to try re-creating the spam filter's database, but any other possible solutions would be welcomed.
Regards,
Cameron