I have a VPS for sending, it is set up as a smarthost to relay from my internal mail server. It is included the SPF record for my domains along with MX records.

I have a VPS for sending, it is set up as a smarthost to relay from my internal mail server. It is included the SPF record for my domains along with MX records. I receive on my firewall at home, that host is what the MX record points at. It is very easy to set up. The full setup for inbound mail is - OpenBSD spamd (greylisting) -> internal postfix Outbound is - internal postfix -> VPS postfix