Emails landing in spam is a deliverability problem with multiple possible causes. This guide helps you identify why your emails are being filtered, fix the underlying issues, and follow best practices to keep your messages in the inbox.
Quick diagnostic
Start by answering these questions to narrow down the cause:
- Are all your emails going to spam, or only emails to specific providers (e.g., Gmail, Outlook)?
- Is this a new problem, or has it always happened?
- Are you sending bulk email (newsletters, marketing), or individual messages?
If only certain providers filter your emails, the issue is likely missing authentication records. If all emails are affected, your server IP may be blacklisted.
Common causes and fixes
SPF tells receiving servers which IP addresses are authorized to send email for your domain. Without a valid SPF record, your emails look suspicious to spam filters.
- Check your DNS for a TXT record starting with
v=spf1 - Make sure you have only one SPF record — multiple SPF records cause both to fail
- Include your HOSTDOG server IP in the record:
v=spf1 +a +mx +ip4:YOUR_SERVER_IP ~all
See How to set up SPF, DKIM, and DMARC records for the complete setup.
DKIM adds a digital signature to your outgoing emails, proving they came from your server and were not modified. Major providers like Gmail and Outlook weigh DKIM heavily in spam scoring.
- In your control panel, go to Email Deliverability and check if DKIM shows as valid
- If it shows a warning, click Repair to auto-generate the DKIM DNS record
DMARC ties SPF and DKIM together and tells receiving servers what to do with emails that fail authentication. Without DMARC, even if SPF and DKIM pass, your domain's trust score may be lower.
- Add a DMARC TXT record to your DNS:
_dmarc.yourdomain.comwith valuev=DMARC1; p=quarantine; rua=mailto:you@yourdomain.com - Start with
p=quarantineand tighten top=rejectonce you confirm all legitimate email passes
If your server's IP address appears on a public blacklist (RBL), many providers will automatically flag or reject your emails. This can happen if another account on the same server sent spam.
- Check your IP at MXToolbox Blacklist Check
- If blacklisted, contact HOSTDOG support — our team can request delisting and investigate the root cause
- HOSTDOG uses Imunify360 to prevent spam from originating on our servers, but false positives can occur
The content of your email can trigger spam filters regardless of authentication. Common triggers:
- Subject lines with ALL CAPS, excessive punctuation (!!!), or words like "FREE", "URGENT", "ACT NOW"
- Large attachments or suspicious file types (.exe, .zip)
- Emails consisting mostly of images with little text
- Too many links, especially to different domains
- Sending identical content to many recipients at once
Some receiving servers check that your server's IP address has a valid reverse DNS (PTR) record. On HOSTDOG shared hosting, this is already configured. If you are on a VPS or dedicated server, contact support to verify your rDNS is set correctly.
How to check your email authentication
Send a test email to a Gmail account, then open it and check the email headers:
- In Gmail, open the email, click the three-dot menu, and select Show original
- Look for the Authentication-Results header
- You should see
spf=pass,dkim=pass, anddmarc=pass
If any of these show fail or none, follow the setup guide for that specific record.
Email sending best practices
- Set up SPF, DKIM, and DMARC — this is the single most impactful step for deliverability
- Use your real name and a professional address —
info@yourdomain.comis better thanxxy123@yourdomain.com - Do not send bulk email from your hosting — use a dedicated email marketing service for newsletters
- Stay within sending limits — Personal plans allow 100 emails/hour, Business plans 1,000 emails/hour
- Include an unsubscribe option in any bulk or recurring emails
- Avoid attachments when possible — use cloud storage links instead
- Write clear subject lines — avoid spam trigger words and excessive formatting
Frequently asked questions
Authentication records improve trust, but they are not the only factor. The server's IP reputation, email content, and sending patterns all play a role. Check your IP against blacklists, review your email content for spam triggers, and make sure you are not exceeding your sending limits. If the problem persists, contact support for help investigating.
While technically possible within your plan's sending limits (100/hour on Personal, 1,000/hour on Business), hosting-based email is not designed for bulk marketing. For newsletters, use a dedicated email marketing service — they have optimized infrastructure, deliverability tools, and built-in compliance features. You can still use your domain as the sender address by configuring SPF and DKIM with the service.
After fixing authentication records and following best practices, most providers update their trust scores within a few days to two weeks. IP reputation takes longer to rebuild — if the IP was heavily blacklisted, it may take a few weeks of clean sending before all providers fully trust it again.