Yep, my ISP has three open resolvers in my assigned range, and another 6 in the alternate range. It it grounds to give them a slight prod?

Your ISP doesn't have 3 open resolvers. Your neighbors have.

Your ISP could terminate the contract with those 3 customers, but they won't - they're customers. They could block inbound trafic on port 25 to those 3 customers (if they knew about it), but they have no incentive to. Or they could block all inbound traffic on port 25, which will likely break DNS for a lot of customers.

you meant port 53, i presume?

I don't believe he/she did as for my ISP blocked port 80 and 443 making me resort to port 25 to send emails~

ups. ofcourse.

I meant that they exist within the ISPs ranges, not that the ISP itself owns them.

I was confused too. It seems the openresolverproject link is reporting more than just open resolvers. Those are active nameservers. I checked two nameserves I had set up at my previous dayjob and was surprised they were on the list. I then checked them manually with dig and found they were in fact not open. Confirmed with this tool: http://dns.measurement-factory.com/cgi-bin/openresolvercheck...

I think the RCODE is important. I also checked 8.8.8.8 but got a result I wasn't expecting.

Very possible that the router provided by the ISP is mis-configured.