How to Improve Email Deliverability

A practical checklist to help your business emails reach the inbox instead of the spam folder.

By Maililo Team · Published 26 September 2026 · Updated 29 September 2026 · 2 min read

Email deliverability is the share of your messages that actually reach the recipient's inbox — not just "delivered" to their server, but not filtered into spam. Here's a practical checklist to improve it.

1. Authenticate your domain

This is the foundation. Receivers like Gmail and Outlook heavily favor authenticated mail.

SPF: one TXT record listing every service that sends as your domain.
DKIM: sign every message; publish the public keys your provider gives you.
DMARC: publish a policy at _dmarc, start with monitoring if unsure, then move to quarantine or reject.

Full explanation: SPF vs DKIM vs DMARC.

2. Make every sending service align

If you send from several tools — your mailbox, an invoicing app, a newsletter service, a help desk — each one must be allowed by SPF and ideally sign with DKIM for your domain. Otherwise DMARC can fail for messages from those tools.

3. Keep a consistent identity

Use the same From domain and a recognizable sender name.
Keep Reply-To on the same domain.
Use your own domain in links rather than link shorteners.

4. Separate conversations from marketing

Send newsletters and promotions from a dedicated marketing service, ideally on a subdomain such as news.yourcompany.com. That way a complaint on a campaign doesn't hurt the reputation of your everyday business mail.

5. Only email people who want to hear from you

Never buy lists.
Use confirmed opt-in for newsletters.
Include a one-click unsubscribe in bulk mail.
Remove people who haven't engaged in a long time.

Spam complaints are one of the strongest negative signals. Google recommends keeping the complaint rate below 0.3%.

6. Clean up bounces

Remove addresses that hard-bounce (for example "mailbox does not exist"). High bounce rates suggest poor list quality.

7. Warm up new domains gradually

A brand-new domain has no reputation. Start with normal one-to-one mail and increase volume slowly over a few weeks before any larger sends.

8. Write like a human

Clear, specific subject lines
A healthy balance of text and images
No misleading subject lines or excessive punctuation
Avoid attachments with macros or executables

9. Monitor

Read your DMARC aggregate reports to spot unknown senders.
Use Show original in Gmail on test messages to confirm SPF, DKIM and DMARC pass.
Google Postmaster Tools shows your domain's reputation if you send enough mail to Gmail users.
Check blocklists if deliverability suddenly drops.

Quick checklist

Seeing specific problems? Read why emails go to spam. Setting up a new domain? Follow custom domain email setup.