How to Improve Email Deliverability: The Complete Checklist

By The EmailCloud Team |
intermediate deliverability

Your Emails Are Probably Landing in Spam (And You Do Not Know It)

Here is a stat that should keep you up at night: roughly 1 in 6 legitimate marketing emails never reach the inbox. They get filtered into spam, promotions tabs, or silently dropped by receiving servers. You never get a bounce notification. You never find out.

The damage is invisible but real. You think you sent an email to 10,000 people. But only 8,300 of them ever had a chance to see it. Your “low open rate” might not be a content problem — it might be a deliverability problem.

This guide gives you 15 concrete steps to fix it. Some take five minutes. Others require a longer commitment. All of them work.

Part 1: Authentication — Your Digital ID Card

Email authentication tells inbox providers that you are who you claim to be. Without it, you are essentially sending letters with no return address. Suspicious by default.

Step 1: Set Up SPF (Sender Policy Framework)

SPF tells receiving servers which mail servers are authorized to send email on behalf of your domain. Without it, anyone can spoof your domain.

Add a TXT record to your DNS with this format:

v=spf1 include:_spf.google.com include:sendgrid.net ~all

The include: entries list your authorized senders — your ESP, Google Workspace, or any other service that sends email from your domain. The ~all at the end means “soft fail emails from unauthorized senders.”

Common mistake: Having multiple SPF records. You can only have one SPF TXT record per domain. If you use multiple sending services, combine them into a single record with multiple include: statements.

Step 2: Configure DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to every email you send. The receiving server checks this signature against a public key in your DNS to verify the email was not tampered with in transit.

Your ESP will generate the DKIM keys for you. Typically, you add a CNAME or TXT record to your DNS that they provide. The process varies by platform:

  • GetResponse: Settings > Domain Authentication > Add Domain
  • ActiveCampaign: Settings > Advanced > I want to set up my own authentication
  • Mailchimp: Account > Domains > Authenticate
  • Kit: Settings > Email > Verify domain

Do not skip this. DKIM is non-negotiable for professional email sending.

Step 3: Implement DMARC (Domain-based Message Authentication)

DMARC ties SPF and DKIM together and tells inbox providers what to do with emails that fail authentication. Start with a monitoring policy:

v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com

This tells servers to send you reports about authentication failures without blocking any emails. After 2-4 weeks of monitoring, tighten the policy:

  • p=quarantine — send failing emails to spam
  • p=reject — block failing emails entirely

Why this matters now more than ever: Since February 2024, Gmail and Yahoo require DMARC for anyone sending more than 5,000 emails per day. Even below that threshold, having DMARC significantly improves your inbox placement.

Step 4: Verify Your Authentication Setup

After configuring all three records, verify they are working. Use our Spam Word Checker to scan your email content, and check your DNS records with a tool like MXToolbox or Google Admin Toolbox.

Send a test email to a Gmail address and click the three dots next to the email. Select “Show original.” Look for these lines:

SPF: PASS
DKIM: PASS
DMARC: PASS

All three should show PASS. If any show FAIL or NEUTRAL, your DNS records need fixing.

Part 2: List Hygiene — Keep Your List Clean or Pay the Price

A dirty list is a deliverability killer. Every bounce, every spam complaint, every email to a dead address chips away at your sender reputation.

Step 5: Remove Hard Bounces Immediately

A hard bounce means the email address does not exist. Continuing to send to hard bounces tells inbox providers you are not maintaining your list — a classic spam behavior signal. Most ESPs automatically suppress hard bounces, but verify this is enabled in your settings.

Step 6: Prune Inactive Subscribers Every 90 Days

Subscribers who have not opened or clicked in 90 days are dead weight. They drag down your engagement metrics, which drags down your sender reputation, which drags down deliverability for everyone else on your list.

Run a re-engagement sequence for inactive subscribers. Anyone who does not re-engage after 3 emails gets removed. Yes, your list will get smaller. Your results will get bigger.

Step 7: Use Double Opt-In

Single opt-in lets anyone enter any email address into your form. That includes fake addresses, typos, spam traps, and bots. Double opt-in requires subscribers to click a confirmation link before being added to your list.

The trade-off: you will get 20-30% fewer subscribers. But those subscribers are real, engaged people who genuinely want your emails. Your open rates, click rates, and deliverability will all improve.

Step 8: Never Buy an Email List

This should go without saying, but it still happens. Purchased lists contain spam traps — email addresses specifically designed to catch spammers. Hitting even one spam trap can get your domain blacklisted instantly.

There is no shortcut here. Build your list organically with opt-in forms and lead magnets. It takes longer. It works better. It is the only approach that does not put your entire domain at risk.

Step 9: Validate Email Addresses at the Point of Collection

Use real-time email validation on your signup forms to catch typos and fake addresses before they enter your list. Services like ZeroBounce, NeverBounce, and BriteVerify integrate with most form builders and ESPs.

This one step can reduce your bounce rate by 80% or more.

Part 3: Sending Practices — How You Send Matters as Much as What You Send

Step 10: Maintain Consistent Sending Volume

Inbox providers watch your sending patterns. If you normally send 2,000 emails per week and suddenly blast 50,000, that looks like a compromised account. Spam filters activate.

Keep your volume consistent. If you need to increase volume (growing list, product launch), ramp up gradually — no more than a 20-30% increase per week. For brand new domains, follow our email warmup guide to build volume safely.

Step 11: Send at Consistent Intervals

Sending three emails on Monday then nothing for two weeks looks erratic. Inbox providers prefer senders with predictable patterns. Pick a schedule and stick to it. Whether that is daily, twice a week, or weekly — consistency matters more than frequency.

Step 12: Watch Your Spam Complaint Rate

Your spam complaint rate must stay below 0.1% — that is 1 complaint per 1,000 emails. Gmail’s threshold is even stricter at 0.08%. If you exceed this consistently, your domain reputation will tank.

To keep complaints low:

  • Make unsubscribing easy. A visible, one-click unsubscribe link in every email. People who cannot find the unsubscribe button hit “Report Spam” instead.
  • Set expectations at signup. Tell people exactly what you will send and how often.
  • Honor preferences. If someone signed up for a weekly newsletter, do not send them daily promotions.

Step 13: Optimize Your Email Content

Spam filters analyze your email content. While modern filters are more sophisticated than simple keyword matching, certain practices still trigger them.

Subject line practices:

  • Avoid ALL CAPS in subject lines
  • Do not use excessive exclamation marks
  • Skip misleading subjects like “RE:” or “FWD:” on non-reply emails
  • Test your subject lines with our Subject Line Grader before sending

Body content practices:

  • Maintain a healthy text-to-image ratio (at least 60% text)
  • Avoid URL shorteners (bit.ly, tinyurl) — spam filters treat these as suspicious
  • Include your physical mailing address (required by CAN-SPAM anyway)
  • Do not use a single large image as your entire email — some clients block images by default

Run your draft emails through the Spam Word Checker to catch trigger words before they cause problems.

Part 4: Reputation Monitoring — Know Where You Stand

Step 14: Monitor Your Sender Reputation

Your sender reputation is a score that inbox providers assign to your domain and IP address. It determines whether your emails go to inbox or spam.

Google Postmaster Tools (free) — shows your domain reputation with Gmail, spam rate, authentication results, and delivery errors. If you send any volume to Gmail addresses, this is essential. Set it up at postmaster.google.com.

Microsoft SNDS (free) — similar insights for Outlook and Hotmail delivery. Register at sendersupport.olc.protection.outlook.com.

MXToolbox — check if your domain or IP is on any blacklists. Run a check monthly, or immediately if you notice a deliverability drop.

Step 15: Check Blacklists Regularly

Getting blacklisted happens to legitimate senders too — a sudden spike in complaints, a compromised form filling your list with spam traps, or an inherited IP address with a bad history.

The major blacklists to monitor:

  • Spamhaus — the most influential blacklist. Being listed here will devastate your deliverability.
  • Barracuda — widely used by corporate email servers.
  • SORBS — catches senders with poor list hygiene.

If you find yourself on a blacklist, most have a delisting process. Fix the underlying issue first (remove the bad addresses, tighten your opt-in process), then submit a delisting request. Recovery takes 1-4 weeks depending on the blacklist.

Your Deliverability Action Plan

Do not try to implement all 15 steps at once. Here is the priority order:

This week (30 minutes):

  1. Check your SPF, DKIM, and DMARC records
  2. Set up Google Postmaster Tools
  3. Review your bounce rate and spam complaint rate

This month (2-3 hours): 4. Enable double opt-in on your signup forms 5. Remove subscribers who have not opened in 90+ days 6. Add email validation to your forms

Ongoing: 7. Monitor Postmaster Tools weekly 8. Run blacklist checks monthly 9. Audit your sending patterns and content quarterly

Deliverability is not a set-it-and-forget-it task. It requires ongoing attention. But the payoff is enormous — the difference between 85% and 97% inbox placement on a 10,000-person list means 1,200 more people see every email you send. Over a year of weekly sends, that is 62,400 additional impressions. From the same list, the same emails, the same effort.

Fix your deliverability first. Everything else in email marketing depends on it.

Frequently Asked Questions

Why are my emails going to spam?

The most common causes are missing email authentication (SPF, DKIM, DMARC), high spam complaint rates, sending to invalid email addresses, being on a blacklist, or poor sender reputation. Use our free Deliverability Score tool to check your domain authentication setup in 30 seconds.

What is a good email deliverability rate?

Aim for 95% or higher inbox placement. Most reputable ESPs achieve 93-98% deliverability for properly authenticated domains with clean sending practices. If your deliverability drops below 90%, you have a significant problem that needs immediate attention.

How long does it take to fix email deliverability issues?

Authentication setup (SPF, DKIM, DMARC) takes 24-48 hours to propagate. Reputation recovery after being blacklisted or having high complaint rates takes 2-6 weeks of consistent good sending behavior. Domain warmup for new domains takes 4-8 weeks.

Do I need all three — SPF, DKIM, and DMARC?

Yes. Gmail and Yahoo now require SPF, DKIM, and DMARC for bulk senders (5,000+ emails/day). Even for smaller senders, having all three significantly improves inbox placement. Use our free SPF Record Builder and DMARC Record Generator to set them up in minutes.