You can write the perfect email and still lose most of your audience if it lands in spam. Email deliverability is the ability to reach the inbox, and it depends on technical setup, reputation and how recipients respond to your messages.

Email deliverability problems: why emails go to spam

  • Missing or misconfigured authentication (SPF, DKIM, DMARC).
  • Poor sender reputation from complaints, bounces or spam traps.
  • Sending to purchased, old or unengaged lists.
  • Sudden spikes in sending volume from a new domain or IP.
  • Content that looks spammy or misleading.
  • Missing or difficult unsubscribe options.

SPF, DKIM and DMARC explained

Email authentication basics
StandardWhat it doesSimple explanation
SPFLists servers allowed to send email for your domain"These services may send on our behalf"
DKIMAdds a cryptographic signature to messages"This email was not altered and came from us"
DMARCTells receivers how to handle failing messages and sends reports"If authentication fails, here is what to do, and tell us about it"

All three are DNS records on your domain. Every service that sends email for you (marketing platform, CRM, support desk, billing system) must be included in SPF and set up with DKIM. Learn more about DMARC at dmarc.org.

Email sender requirements from major providers

Since 2024, Gmail and Yahoo have enforced stricter requirements for bulk senders. Google's email sender guidelines include:

  • Authenticate email with SPF and DKIM, and publish a DMARC policy (bulk senders).
  • Align the From domain with SPF or DKIM.
  • Provide one-click unsubscribe for marketing messages and honour requests promptly.
  • Keep spam complaint rates low, monitored in Google Postmaster Tools.
  • Use valid forward and reverse DNS for sending servers.

Even if you send smaller volumes, following these rules improves inbox placement.

Protecting domain reputation

Use permission-based lists

Send only to people who opted in. Never buy lists. Use confirmed opt-in for high-risk sign-up sources.

Clean your list regularly

Remove hard bounces immediately, suppress addresses that have not engaged for a long period, and run re-engagement campaigns before removing inactive subscribers.

Warm up new domains and IPs

Start with small volumes to your most engaged contacts and increase gradually over several weeks.

Separate sending streams

Consider using subdomains for marketing (for example news.yourdomain.com) and transactional emails so problems in one stream do not affect the other.

Send consistently

Regular sending patterns build trust. Large, irregular blasts look suspicious.

Content practices that help

  • Clear sender name and honest subject lines.
  • Balanced text and images; avoid image-only emails.
  • Working links to reputable domains.
  • A visible unsubscribe link and physical address where required.
  • Relevant content that people open and click.

Email deliverability checklist

  1. SPF includes every service that sends email for your domain.
  2. DKIM signing is enabled for each sending service.
  3. A DMARC record is published and reports are monitored.
  4. The From domain aligns with SPF or DKIM.
  5. Marketing emails include one-click unsubscribe and honour requests quickly.
  6. Lists are permission-based, and bounces are suppressed automatically.
  7. Inactive subscribers are re-engaged or removed periodically.
  8. Sending volume increases gradually for new domains and IPs.
  9. Spam complaint rates are monitored at major providers.
  10. Transactional and marketing streams are separated where possible.

Monitoring deliverability

Deliverability monitoring tools and signals
SignalWhere to check
Spam complaint rateGoogle Postmaster Tools, ESP reports
Bounce rateEmail platform reports
DMARC reportsDMARC report processor
Inbox placementSeed testing tools
Engagement trendsClick and reply rates by mailbox provider

A sudden drop in engagement at one provider (for example Gmail) is often an early sign of deliverability problems there.

Fixing emails going to spam

  1. Check authentication with an online checker and your email platform's domain settings.
  2. Review DMARC reports for unauthorised or misconfigured senders.
  3. Pause sending to unengaged segments.
  4. Reduce volume and send to your most engaged contacts first.
  5. Review recent changes: new lists, new content types, new sending tools.
  6. Monitor complaint rates daily until stable.

Deliverability and marketing automation

Automated sequences send continuously, so problems compound quickly. Review sequences regularly, suppress contacts who never engage and make sure each automation respects unsubscribes across all tools. Our B2B email marketing guide covers broader practices, and our lead nurturing strategy explains sequence design.

If your emails are landing in spam or you are setting up a new sending domain, our email automation team can audit DNS records, configure authentication and build healthy sending practices.

Frequently asked questions

What is a good email deliverability rate?
Aim for very low bounce and complaint rates and strong inbox placement. Monitor your own trends by mailbox provider rather than relying on a single benchmark.
Do I need DMARC?
Yes for bulk senders to major providers, and it is recommended for all organisations because it protects your domain from spoofing and gives visibility into who sends email for you.
Why are my emails going to spam in Gmail?
Common causes include missing authentication, high complaint rates, sending to unengaged contacts, sudden volume spikes and content that looks spammy.
What is one-click unsubscribe?
A standard that lets recipients unsubscribe directly from the email client without visiting a website, required by major providers for bulk marketing email.