Re: SPF
If only recipients used SPF!
You know a lot of places don't bother with SPF? All the domains I manage have their SPF properties correctly set but I still get lots of bounced mails where the originals claim to be from one of my domains..
And it's quite clear (looking at the headers) that the scumbags that sent them are using mail servers that don't even make a pretense of looking at SPF (my servers are neither in Brazil nor Russia. Or Thailand or China[1] or some parts of Eastern Europe).
[1] A lot of those places are geo-blocked on my firewall - I know it's not going to block everything but it does vastly reduce the attacks on my webservers and also the amount of spam that I get. And every little helps.