Email Deliverability Checklist 2026: 20 Things to Check Before You Send

Email deliverability has never been more complex. Google and Yahoo's 2024 requirements introduced mandatory SPF, DKIM, and DMARC for bulk senders. Spam filters have become more sophisticated. Blacklists have proliferated. And inbox placement — the percentage of your emails that actually reach the inbox — is harder to maintain than ever.

This checklist covers every factor that affects whether your emails reach the inbox in 2026.

1. SPF record published: A valid SPF TXT record exists at your domain root. 2. SPF lookup limit not exceeded: Your SPF record performs 10 or fewer DNS lookups. 3. SPF ends with -all or ~all: Hard or soft fail specified for unauthorized senders. 4. DKIM key published: A valid DKIM TXT record exists at your selector._domainkey subdomain. 5. DKIM key is 2048 bits: 1024-bit keys are weak; Google recommends 2048. 6. DKIM selector active: The selector matches what your mail server is signing with. 7. DMARC record published: A valid DMARC TXT record exists at _dmarc.yourdomain.com. 8. DMARC policy is quarantine or reject: p=none provides no protection; upgrade to p=quarantine or p=reject. 9. DMARC reporting configured: Both rua (aggregate) and ruf (forensic) addresses set. 10. DMARC alignment passes: Your From domain aligns with SPF and/or DKIM.

• ·SPF record published at domain root (v=spf1 ...)
• ·SPF has 10 or fewer DNS lookups (use SPF checker to count recursively)
• ·SPF ends with -all (hard fail) or ~all (soft fail)
• ·DKIM key published at selector._domainkey.yourdomain.com
• ·DKIM key is 2048-bit minimum
• ·DKIM selector matches what your mail server is actively signing with
• ·DMARC record at _dmarc.yourdomain.com
• ·DMARC policy is p=quarantine or p=reject (not p=none)
• ·DMARC rua= reporting address configured and mailbox active
• ·DMARC alignment passes for all legitimate sending services

11. Not listed on major blacklists: Check against Spamhaus ZEN, Barracuda BRBL, SpamCop, UCEPROTECT, SpamRATS, Abusix, and others. 12. Sender score above 80: Check your IP reputation at Senderscore.org. 13. Google Postmaster Tools connected: Monitor spam rate, domain reputation, and IP reputation directly from Gmail's perspective. 14. Microsoft SNDS registered: Get feedback on your IP reputation with Outlook/Hotmail. 15. Feedback loop (FBL) active: Register for FBLs with major ISPs to receive spam complaint notifications.

• ·Domain and sending IP clean on all major blacklists (Spamhaus, Barracuda, SpamCop, UCEPROTECT, SpamRATS, Abusix)
• ·Automated blacklist monitoring configured with instant alerts (new listings caught within 15–60 minutes)
• ·Google Postmaster Tools registered and showing domain reputation 'High'
• ·Spam rate below 0.10% in Google Postmaster Tools (ideally below 0.05%)
• ·Microsoft SNDS registered and showing green status for sending IPs

16. Reverse DNS (PTR) record set: Your sending IP has a PTR record pointing to a hostname that resolves back to your IP (forward-confirmed rDNS). 17. MTA-STS policy published: Enforce TLS for inbound connections to your mail server. 18. TLS-RPT configured: Receive reports about TLS delivery failures. 19. BIMI record published (optional): Display your brand logo in Gmail, Apple Mail, and Yahoo when DMARC p=reject is in place. 20. Subdomain spam isolation: Separate subdomains for marketing email (e.g., mail.yourdomain.com) protect your primary domain reputation.

• ·PTR (reverse DNS) record configured — sending IP resolves to mail server hostname and hostname resolves back to same IP (FCrDNS)
• ·MTA-STS policy file hosted at https://mta-sts.yourdomain.com/.well-known/mta-sts.txt with mode: enforce
• ·MTA-STS DNS record published at _mta-sts.yourdomain.com
• ·TLS-RPT record at _smtp._tls.yourdomain.com for TLS failure reporting
• ·Marketing email sent from separate subdomain (e.g., mail.yourdomain.com) to isolate reputation

Beyond infrastructure, how you send matters as much as where you send from:

• Use confirmed double opt-in for new subscribers • Remove hard bounces immediately after the first occurrence • Suppress unengaged subscribers after 6 months • Never purchase or rent email lists • Keep your spam complaint rate below 0.1% (Gmail) and 0.08% (Yahoo) • Warm new IP addresses gradually over 2-4 weeks • Send consistently — sporadic large bursts trigger spam filters • Include a visible, one-click unsubscribe link (required by Gmail/Yahoo since 2024)

• ·Double opt-in used for all new subscribers
• ·Hard bounces removed immediately after first occurrence — never retry
• ·Spam complainers suppressed immediately and permanently
• ·Unengaged subscribers (no opens in 6+ months) suppressed after re-engagement campaign
• ·No purchased, rented, or scraped email lists used
• ·Spam complaint rate below 0.10% at Gmail (monitor in Postmaster Tools)
• ·One-click unsubscribe (List-Unsubscribe-Post header) implemented
• ·New IPs warmed up gradually — never start at full volume on a cold IP

Run through this checklist quarterly or whenever you notice delivery problems. Use IsMyEmailBlacklisted to automate most of the checks:

• Blacklist status: Checked against all 60 major lists automatically • SPF validation: Syntax, lookup count, and include directives analyzed • DKIM verification: Records checked across 23 common selectors • DMARC analysis: Policy strength, alignment, and reporting configuration • Reverse DNS: PTR record validation and forward-confirmed rDNS check • SMTP security: TLS support, open relay, and banner fingerprinting

Automate the monitoring so you catch issues immediately rather than discovering them after delivery starts failing.