All email guides
A technical documentation library for authentication, DNS, deliverability and troubleshooting.
SPF setup guide
Set up SPF records correctly and avoid common mistakes.
DKIM explained
Selectors, keys and validating DKIM signatures.
DMARC guide
Policies, alignment and getting to enforcement safely.
Email deliverability basics
Reputation, engagement and inbox placement fundamentals.
DNS basics for email
MX, A, PTR and authentication records.
General email troubleshooting
A practical path for diagnosing email problems.
SPF flattening guide
When flattening helps and when it creates risk.
SPF too many lookups
Fix SPF permerror caused by includes and redirects.
Why email goes to Gmail spam
Gmail-specific checks and likely causes.
Microsoft 365 DKIM setup
Understand the DNS and activation steps.
Mailgun SPF and DKIM
Authenticate a Mailgun sending domain properly.
PTR records for email
Reverse DNS and HELO trust signals.
Email warm-up guide
Safer volume ramping and expectations.
How to read DMARC reports
Turn aggregate reports into action.
Subdomain vs root domain for sending
Choose the right domain strategy.
Gmail bulk sender basics
Core rules for higher-volume senders.