Email Deliverability
Email deliverability is the likelihood that your email lands in the inbox rather than spam or a rejection. It is not one setting; it is the result of authentication, IP/domain reputation, list quality, and sender behavior.
Three authentication layers
| Layer | Role |
|---|---|
| SPF | Declares which servers may send on behalf of the domain |
| DKIM | Signs the message so the content cannot be altered |
| DMARC | Sets policy when SPF/DKIM fail and sends reports |
They complement each other. SPF alone is not enough; DMARC without DKIM is often weak.
Reputation factors
- IP reputation — a shared IP can be tainted by another provider.
- Domain reputation — domain age, volume, and complaints.
- List hygiene — hard bounces, spam traps, and inactive addresses.
- Engagement — opens, clicks, and replies help positive signals.
- Content — suspicious links, unsolicited attachments, and clickbait subjects.
What to watch for
- Never buy an email list. Use double opt-in.
- Monitor bounces and complaints. Stop sending to hard-bounced addresses.
- Warm up a new IP. Send gradually, not hundreds of thousands at once.
- Separate transactional and marketing mail. Their reputations can affect each other.
- Use a dedicated service for high volume. Shared hosting is not for bulk email.
- Read DMARC reports. Aggregate reports show who is sending on behalf of your domain.
Send to several email providers and check the spam folder. Monitor bounces, complaints, and domain reputation in Google Postmaster or a similar tool. If a problem starts after a DNS change, revert it and test one variable at a time.
Common record examples:
| Record | Example |
|---|---|
| SPF | v=spf1 include:_spf.google.com ~all |
| DMARC | v=DMARC1; p=none; rua=mailto:[email protected] |
| DKIM | selector._domainkey → the value from your email provider |
Start DMARC with p=none to monitor, then move to quarantine after the reports are clean.
FAQ
Is SPF enough?
No. SPF checks the sending server, but DKIM signs the content and DMARC provides policy and reporting.
Why does email go to spam even with correct SPF/DKIM?
Authentication is not the only factor. IP/domain reputation, engagement, content, and complaints also matter.
Is shared hosting suitable for email marketing?
Usually not for high volume. Use a transactional/marketing email service with reputation and monitoring tools.
Disclaimer: Hosting Wiki articles are prepared for educational and reference purposes. Hosting technology keeps evolving, so some technical details may change over time.