I wish it were that clear cut. You also have a role to protect your customers against threats, and to ensure that their mailbox is at least usable rather than deluged with spam. Being proactive about postmaster complaints and being sensitive to false positives in filtering is a useful middle path and a widely defined best practice. Never mind that quite a few large players don’t follow it. --srs On 13/02/17, 8:43 AM, "anti-abuse-wg on behalf of peter h" <anti-abuse-wg-bounces@ripe.net on behalf of peter@hk.ipsec.se> wrote: As my wife urged me to clarify things :-) The role for an ISP in fighting abuse is to detect and prevent it's customer from sending malware & spam out of it's network. Not filter incoming stuff, that would be censoring.