How to improve email deliverability, 12 practices that actually matter

Deliverability is whether your email reaches the inbox rather than the spam folder or nowhere at all. It is decided by mailbox providers, using signals you partly control: who you are (authentication), who you send to (list quality and consent), how you send (volume and consistency) and how people react (opens, replies, deletes and spam reports).

No one can guarantee inbox placement, and anyone who promises it is guessing. But the practices below are the ones that consistently move the signals in your favor. They are ordered roughly from foundation to fine-tuning.

1. Authenticate your domain with SPF, DKIM and DMARC

Authentication proves your mail really comes from you. Without it, providers have little reason to trust you, and as of 2026 Gmail and Yahoo require SPF, DKIM and DMARC from bulk senders.

• Publish one SPF record that includes every service sending as your domain.
• Enable DKIM signing with your own domain, not your provider's.
• Publish a DMARC record, starting at p=none, and read the reports.

The alignment details are covered in SPF, DKIM and DMARC explained. In InboxRoads, adding a sending domain generates all three records for you.

2. Send from a domain you control

Use an address on your own domain, such as news@example.com, rather than a free mailbox like a gmail.com address. Some free mailbox providers publish strict DMARC policies, so mail sent in their name through a third-party platform can fail authentication, and Google's sender guidelines specifically tell you not to impersonate Gmail in the From header. Many senders use a subdomain for marketing (for example, mail.example.com) so its reputation is separate from day-to-day company mail.

3. Verify your list before sending

Invalid addresses cause hard bounces, and a high bounce rate tells providers you are not maintaining your list. Verify every imported list, and re-verify lists you have not mailed in a few months. Remove invalid, domain-error and mailbox-error results, and handle risky ones with care.

The full process is in how to verify an email list, and you can check a single address with the free email verifier.

4. Only email people who asked to hear from you

Consent is the single biggest factor in complaint rates. People who did not sign up mark mail as spam, and complaints hurt more than almost any other signal.

• Never buy, rent or scrape lists.
• Say clearly at signup what people will receive and how often.
• Consider double opt-in for new signups. It confirms both that the address works and that the person wanted to join. See double opt-in vs single opt-in.

5. Keep volume consistent and warm up new domains

Providers are wary of sudden spikes, especially from domains they have not seen before. A brand-new sending domain has no reputation yet, good or bad.

• Start a new domain with your most engaged recipients, in smaller sends.
• Increase volume gradually over a few weeks as results stay healthy.
• Avoid long silences followed by a blast to your entire database.
• Keep a predictable schedule so volume is steady week to week.

There is no universal warm-up schedule. Watch bounces, complaints and inbox placement, and slow down if they worsen.

6. Send based on engagement and sunset inactive contacts

Contacts who have not opened or clicked in a long time drag down engagement signals and are more likely to be abandoned addresses.

1. Build a segment of contacts with no opens or clicks over a period that suits your send frequency, such as six to twelve months for a monthly newsletter.
2. Send them a short re-engagement message asking if they still want to hear from you.
3. Stop mailing anyone who does not respond.

Keep in mind that open tracking is imperfect. Some mail apps preload images, which records opens that did not happen, and others block images, which hides real opens. Clicks and replies are stronger signals.

7. Make unsubscribing easy

A hard-to-find unsubscribe link does not keep subscribers. It turns them into spam complaints. Include a visible unsubscribe link and RFC 8058 one-click unsubscribe headers, and process requests immediately. Gmail and Yahoo require one-click unsubscribe for bulk marketing mail. InboxRoads adds both the link and the headers to every marketing email, and suppresses unsubscribes automatically.

8. Keep content and links clean

Spam filters look at content alongside reputation. You do not need to fear individual words, but avoid patterns associated with spam:

• A sensible text-to-image balance. Avoid emails that are a single large image.
• No URL shorteners. They hide the destination and are often abused.
• Links to reputable, working pages, ideally on your own domain.
• Subject lines that match the content. Misleading subjects drive complaints.
• Clean HTML without hidden text or broken tags.

9. Use a tracking domain on your own domain

Open and click tracking rewrites links to go through a tracking domain. If that domain is shared with many other senders, their reputation can affect yours. A custom tracking domain, such as a CNAME at track.example.com, keeps your links on your own brand and reputation. In InboxRoads, you can set one up alongside your sending domain.

10. Include a plain-text version

A multipart email with both HTML and plain-text parts is the standard format, and some recipients and mail clients prefer or require text. It is a small effort that makes your mail look like normal, well-formed mail.

11. Monitor bounces, complaints and provider tools

What you do not measure you cannot fix. Watch these after every campaign:

Google's ceiling for user-reported spam is 0.3%, and it recommends staying below 0.1%. Learn the difference between bounce types in hard bounce vs soft bounce. InboxRoads also auto-pauses a campaign if bounce or complaint rates cross set thresholds, which limits the damage from a bad list.

12. Test before every send

Send a test email to yourself and a colleague before every campaign. Check:

• Merge tags render correctly, with fallbacks (for example, {{first_name|there}}) for missing data.
• Every link works and goes where it should.
• The email reads well on mobile and with images turned off.
• The From name, subject and preview text look right in the inbox.
• Authentication passes. Look for spf=pass, dkim=pass and dmarc=pass in the message headers.

Key takeaways

• Authentication and alignment are the foundation. Without them, nothing else works reliably.
• List quality and consent matter more than any content trick. Verify lists and never buy them.
• Complaints hurt more than almost anything else, so make unsubscribing effortless.
• Grow volume gradually and send to people who engage.
• Measure after every campaign, and treat Google's 0.3% spam rate as a ceiling, not a goal.
• No practice guarantees the inbox. Together, they give you the best realistic chance.