DNS Propagation
The time it takes for DNS record changes to spread across all DNS servers worldwide.
When you update DNS records (SPF, DKIM, DMARC, MX, CNAME), the changes don't take effect instantly. DNS propagation typically takes 15 minutes to 48 hours, though most changes propagate within 1-4 hours.
During propagation, some servers may see your old records while others see the new ones. This can temporarily affect email authentication and deliverability.
Best practices: make DNS changes at least 48 hours before starting email campaigns, lower the TTL (Time To Live) before making changes to speed up propagation, and verify your records using MXToolbox or similar tools before sending.