How email delivery works, for the person who has to decide.
How delivery works, what mailbox providers require, and what to check, whatever platform you send from. Every article lists the sources it draws on.
Start here
Where to begin, before any protocol.
Is This a Delivery Problem? How to Tell Before You Spend Money
For a marketing lead or business owner: how to tell a real delivery problem (bounces, blocks, mail filed as spam) from a list, content or measurement problem, using only evidence you can reach without server logs, and what each finding means for the decision.
What Mailbox Providers Measure, and Who on Your Team Owns Each Part
The signals mailbox providers score (complaints, engagement, bounces, spam traps, authentication and volume patterns), each assigned to the person who can act on it (marketing, whoever runs DNS, or the sending platform) with that owner's first action.
Reading a Domain Check Result
What SPF, DKIM, DMARC, MX and blocklist results mean when the domain check says good, risky, bad or unknown, what the check cannot see (selectors it didn't try, the addresses you actually send from, your reputation), and the next step for each.
All topics
Foundations
5 articles- Foundations of Email Deliverability
- The Seven-Step Delivery Model
- Is This a Delivery Problem? How to Tell Before You Spend Money
- What Mailbox Providers Measure, and Who on Your Team Owns Each Part
Strategy
1 articleMailbox Providers
15 articles- Gmail Email Sender Guidelines
- Gmail SMTP Errors and Troubleshooting
- Yahoo Sender Requirements & Best Practices
- Yahoo Complaint Feedback Loop (CFL)
Postmaster Tools
2 articles- All articles →
Authentication
13 articles Transport Security
7 articles- MTA-STS (SMTP MTA Strict Transport Security, RFC 8461)
- SMTP TLS Reporting (TLS-RPT, RFC 8460)
- DANE for SMTP (RFC 7672)
- SMTP TLS in Practice (STARTTLS, Implicit TLS, REQUIRETLS, version floors)
RFCs
8 articles- RFC 5321 — SMTP: The Transport Protocol
- RFC 5322 — Internet Message Format
- RFC 5598 — Internet Mail Architecture
- ESMTP Extensions for Senders — SIZE, PIPELINING, CHUNKING, DSN
List Management
4 articlesBounce Handling
3 articlesIP Management
3 articlesOperations
18 articles- Deliverability Metrics and Benchmarks
- List Hygiene and Sunset Policies
- Sending Infrastructure Practices
- MTA Delivery Tuning
ESP Operations
16 articles- Abuse Desk Operations
- ESP Outbound Monitoring Systems
- Customer Vetting for ESPs
- Vetting Transactional Email Accounts
ESP Guides
10 articles- ActiveCampaign: DKIM and DMARC setup
- Brevo: DKIM and DMARC setup
- Cakemail: DKIM and DMARC setup
- Constant Contact: DKIM and DMARC setup
Industry Best Practices
5 articles- M3AAWG Sender Best Common Practices (Version 4.0)
- M3AAWG Email Authentication Recommended Best Practices (2020)
- M3AAWG Sending Domains Best Common Practices
- M3AAWG Documents for Senders and ESPs — Annotated Index
Reference
14 articles- Deliverability Glossary
- Email Abuse Taxonomy
- DNS Blocklists and the Spamhaus Zones
- Spamhaus Listings Deep Dive — SBL, CSS, PBL, DBL Policy and Delisting
Compliance
18 articles- CAN-SPAM Act (United States)
- CAN-SPAM Rulemaking (16 CFR Part 316)
- CASL — Canada's Anti-Spam Legislation
- Email-Law Enforcement: CASL Cases and CAN-SPAM Statutory Detail
Check while you read
See what your own domain publishes, free.
Can't find your situation?
Our services start from what you are seeing, each with its scope and its price.
See the services →