Deliverability Best Practices
Best practices to ensure your emails reach the inbox.
Email Content
Subject Lines
- Keep them under 50 characters
- Be clear and descriptive
- Personalize when possible
- Test different variations
Avoid:
- Excessive capitalization
- Too many exclamation marks
- Spam trigger words
- Misleading promises
Email Body
- Use a clear structure
- Include a clear call-to-action
- Keep paragraphs short
- Use images with alt text
- Write for mobile devices
Avoid:
- Too many different colors
- Too many links
- Overloading with images
List Management
Clean Your List
- Remove bounced addresses immediately
- Clean inactive subscribers (6-12 months)
- Segment your list
- Try to re-engage before removing
Never use purchased email lists. This will damage your sender reputation.
Unsubscribe Handling
- Provide clear unsubscribe links
- Process unsubscribes within 24 hours
- Honor preferences promptly
Bounce Management
Hard Bounces - Remove immediately:
- Invalid email addresses
- Blocked domains
Soft Bounces - Retry temporarily, then remove:
- Mailbox full
- Server temporarily unavailable
Authentication
Set up SPF, DKIM, and DMARC records with your email provider. See the Resend Integration guide for detailed setup instructions.
Testing Before Sending
Always test your emails before sending:
- Send to yourself - Check formatting and links
- Test on mobile - Most emails are read on phones
- Test email clients - Gmail, Outlook, Apple Mail
- Verify all links work correctly
Monitoring Performance
Track these key metrics in your Resend dashboard:
- Open Rate - Percentage of recipients who opened your email
- Click Rate - Percentage of recipients who clicked a link
- Bounce Rate - Emails that failed to deliver (remove these addresses immediately)
- Unsubscribe Rate - Recipients who opted out
Use Gmail Postmaster Tools to monitor:
- Spam rate
- IP reputation
- Domain reputation
- Feedback loop reports
Warning Signs
- Increasing bounce rate - Clean your list
- Declining open rate - Review subject lines and sender reputation
- High spam complaints - Review content and list quality
Warming Up New Domains
Gradually increase volume when setting up a new sending domain:
- Week 1: 50-100 emails/day
- Week 2: 200-500 emails/day
- Week 3: 1,000 emails/day
- Week 4+: Full capacity
Common Mistakes
- Using link shorteners (bit.ly, tinyurl)
- Deceptive subject lines
- Missing unsubscribe links
- Using no-reply addresses
See how to avoid Gmail's spam folder and how to avoid Outlook's spam folder for more details.