I run my own mail server even though my ISP blocks port 25 OUTBOUND. I use DynDNS's Mail relay service. Only costs about $20/yr. I never have have a problem being flagged as spam or anything else. I can receive mail on port 25 INBOUND with no issues. I set my MX RR to my home IP and add a secondary to a dynamic address, also through DynDNS. works great!