Deliverability problems are rarely one big failure — they are an accumulation of small misconfigurations. This is the 20-point audit we run for every new corporate customer, in the order that surfaces problems fastest. Work through it top to bottom.

Section 1: DNS Fundamentals (Points 1–5)

  1. MX records point at the correct mail servers with sensible priorities.
  2. Exactly one SPF record exists, lists all real senders, ends in ~all or -all, and stays under 10 lookups.
  3. DKIM is enabled and passing for every sending platform, including newsletter tools.
  4. DMARC record exists, reports are being collected, and policy is quarantine or reject on mature domains.
  5. Reverse DNS (PTR) on the sending IP resolves to a hostname matching the mail server — a classic silent killer on self-hosted servers.

Section 2: Reputation (Points 6–10)

  1. Sending IP is clean on major blacklists.
  2. Domain is clean on domain-based blocklists.
  3. Google Postmaster Tools is set up and shows domain reputation medium or better.
  4. Shared hosting neighbours are not poisoning your shared IP — if they are, plan a move.
  5. No history of sudden volume spikes or compromise in the past 90 days.

Section 3: Sending Behaviour (Points 11–15)

  1. Bounce rate under 2% — remove dead addresses ruthlessly.
  2. Spam complaint rate under 0.1%.
  3. Bulk mail rides a dedicated platform and subdomain, not the office mail server.
  4. All marketing mail has working one-click unsubscribe — required by Gmail and Yahoo for bulk senders.
  5. Volume is consistent day to day rather than spiky.

Section 4: Content and Technical Hygiene (Points 16–20)

  1. Messages contain a plain-text alternative alongside HTML.
  2. Links point at your real domain, not shorteners; no mismatched link text.
  3. Attachment habits are sane — invoices as PDF, never as ZIP or executables.
  4. From name and address are stable and recognisable.
  5. Test messages score cleanly on a mail-tester service and land in inbox at Gmail, Outlook and Yahoo test accounts.

Scoring Yourself

Points passingVerdict
18–20Healthy — monitor quarterly.
13–17Fix the gaps this month; you are leaking mail.
Under 13Serious — expect spam-folder placement until remediated.

Why Point 5 (Reverse DNS) Trips Up So Many Self-Hosted Setups

Reverse DNS deserves special attention because it is the one item on this list that a website owner cannot fix through their own hosting control panel — it requires the IP's actual owner (your hosting or VPS provider) to configure it correctly on their end. Many self-managed VPS or dedicated mail servers in Nepal send mail from an IP whose PTR record still points at a generic hostname assigned by the data center, rather than the mail server's actual domain name; several major inbox providers treat this mismatch as a meaningful spam signal on its own. If points 1 through 4 all check out but deliverability is still poor on a self-hosted server, a reverse DNS mismatch is one of the first things worth confirming with the hosting provider directly.

Frequently Asked Questions

How often should the audit run?

Quarterly for normal businesses; monthly if email drives revenue directly (e-commerce, travel bookings, SaaS).

Which single fix moves the needle most?

Usually authentication — a domain going from no SPF/DKIM/DMARC to all three aligned sees the biggest single jump in inbox placement.

Can this checklist be run on a platform like Google Workspace, or only self-hosted mail?

Most of it applies regardless of platform — DNS, authentication, sending behavior and content hygiene are your responsibility either way; only reverse DNS and IP reputation are largely handled for you automatically on a managed platform like Google Workspace or Zoho.

Want the audit done for you? It is included free with corporate email hosting — or request a one-off deliverability check on your current email setup.