Email checklist

Every rule in the email playbook, by chapter, required rules first. Each links to its own page with how we built it and how to check it.

Message basics

• Required Send the headers every message needs
• Required Include a plain-text part
• Required Encode everything as UTF-8
• Required Declare the language and text direction
• Required Keep messages small
• Recommended Point replies to a mailbox someone reads
• Recommended Accept international addresses
• Recommended Mark automated messages

Sending domain and authentication

• Required Publish an SPF record
• Required Sign every message with DKIM
• Required Enforce DMARC
• Required Lock down domains that never send mail
• Required Give sending servers matching DNS names
• Required Send and receive over TLS
• Optional Pin mail TLS with DANE
• Optional Keep authentication through forwarders with ARC
• Optional Show your logo with BIMI

Deliverability

• Required Meet the bulk sender rules
• Required Warm up new domains and addresses
• Required Send only to people who asked
• Required Keep the list clean
• Recommended Separate transactional and marketing mail
• Recommended Watch your sender reputation
• Recommended Use a steady sender identity
• Recommended Write mail that does not look like spam

Unsubscribe and bounces

• Required Offer one-click unsubscribe
• Required Unsubscribe within two days
• Required Show an unsubscribe link in the message
• Required Keep transactional mail free of marketing
• Required Stop on permanent failures and retry temporary ones
• Required Retry with backoff and give up in time
• Required Stop at the first complaint
• Required Accept mail at postmaster and abuse
• Recommended Label list mail
• Optional Let people choose what they get

Layout and accessibility

• Required Mark up the message with meaning
• Required Describe every image
• Required Use contrast and more than colour
• Required Make email text easy to read
• Required Send text instead of pictures of text
• Required Fit every screen
• Required Make buttons easy to tap
• Required Test in the clients your readers use
• Recommended Build layout that Outlook can show
• Recommended Inline the CSS and plan for it to fail
• Recommended Plan for dark mode
• Recommended Write a preheader

Email privacy

• Required Keep personal data out of links
• Required Send only what the message needs
• Required Keep proof of consent
• Required Keep email logs lean
• Required Never email customers from test systems
• Recommended Don't rely on tracking pixels

Email security

• Required Never let visitors pick who gets your mail
• Required Send only links people can trust
• Required Make your mail hard to fake
• Required Make sign-in and reset links single-use and short-lived
• Required Keep secrets out of email
• Recommended Avoid risky attachments
• Optional Sign or encrypt sensitive mail
• Avoid Send no scripts or forms in email

Automation and agents

• Required Send each message once
• Required Put the facts of a receipt in text
• Required Treat incoming email as untrusted
• Recommended Send calendar invites that update correctly
• Recommended Write mail that assistants can read safely
• Optional Add structured data to orders and bookings