Finally configured proper email deliverability, inbox rate 99%

Dear/madam,

After six months of struggle only, I have achieved inbox rate 99% for transactional email from my OVHcloud VPS. This journey itself was most educational, and I am sharing the complete methodology below so that others may benefit.

1. Reverse DNS (rDNS) must match the HELO/EHLO hostname exactly. OVHcloud configured this only after three tickets.
2. SPF record with strict "-all" mechanism; no "include" for third-party senders.
3. DKIM 2048-bit key rotated quarterly; I use opendkim with selector rotation.
4. DMARC policy p=quarantine, rua= to own mailbox for monitoring.
5. IP warming: 50 messages day one, doubling each week to current 8,000/day.
6. Abuse desk response time under 4 hours; I check mailbox every two hours itself.
7. FCrDNS validation passed at all major providers.
8. TLS 1.3 enforced; no fallback to plaintext.
9. List-unsubscribe header present in all marketing traffic (10% of volume only).
10. Registered with SNDS, Google Postmaster, Yahoo CFL; all green now.

Kindly share your own deliverability tips. I am most interested in IPv6 reputation strategies.

# verify rDNS matches
dig -x 203.0.113.47 +short
# should return: hetzner.com

Congratulations very much your journey is inspiration

1. I set up similar on KnownHost
2. But my IPv6 rate is like 60% only
3. SNDS say "no data" very much

How to say... I think my IPv6 subnet is blacklisted before I get it. Very frustrating. Your tip number 7 is new to me, I check check rate now.

Very much appreciate your guide

Priya your checklist very thorough. I will save this for when my two server need mail. Currently I use third-party only.

XD the irony is not lost on me — I run postfix for internal alert but outsource customer mail to Vultr. Their IP already warm, my time not spent on abuse desk.

# my "deliverability" is one line in docker-compose
services:
  mail:
    image: bytemark/smtp
    environment:
      RELAY_HOST: vultr.com

Will you make this into script? Automated check for rDNS, SPF, DKIM? I will pay for such tool.