Knowledge Base
Find answers to common questions, troubleshooting guides, and best practices for using Lettr.Popular Topics
Delivery Issues
Troubleshoot email delivery problems
Authentication
Fix API key and authentication issues
Deliverability Tips
Improve your email deliverability
Security Best Practices
Secure your integration
Browse by Category
Troubleshooting
- Delivery Issues - Why emails aren’t being delivered
- Authentication - API key and auth problems
- Rate Limits - Understanding and handling rate limits
Best Practices
- Deliverability - Maximize inbox placement
- Security - Protect your account and data
- Templates - Design effective email templates
Quick Answers
Why isn't my email being delivered?
Why isn't my email being delivered?
Check your domain verification status, ensure the recipient isn’t suppressed, and verify you’re not hitting rate limits. See Delivery Issues for detailed troubleshooting.
How do I verify my domain?
How do I verify my domain?
Add the DNS records shown in your dashboard, wait for propagation (15 min to 48 hours), then click Verify. See Domains for details.
What's the API rate limit?
What's the API rate limit?
Free: 10 req/sec, Pro: 100 req/sec, Enterprise: Custom. See Rate Limits.
How do I track email opens?
How do I track email opens?
Open tracking is enabled by default. View stats in the dashboard or via the API. See Analytics.