Eh, you have the wrong approach. Just do everything and assume they all contribute to reputation. Maximise, don't minimise, your appearance of being a well-run

Eh, you have the wrong approach. Just do everything and assume they all contribute to reputation. Maximise, don't minimise, your appearance of being a well-run ESP that takes internet citizenship seriously. For example, zone signing: I don't know if it makes a difference to domain reputation, but it might, so I do it. DMARC is not a nuclear option, no-one starts out with the reject policy, in fact most of my domains are still p=none and I monitor the reports. You absolutely can and should - irrespective of how much information it gives you in return - verify your domains in Google's Postmaster Tools, monitor your IP addresses and junk mail tagging at Hotmail via Microsoft SNDS/JMRP, and setup DMARC reporting e.g. using Postmark's weekly digest. I strongly suspect your lack of TLS is hurting you in particular. For this and other reasons besides I advise you to enable TLS for all inbound and outbound. And use a real cert.