Email deliverability, taught from zero. Plainly.

The plumbing, in plain English: how a message actually travels, and where deliverability lives.

1. 1
   What happens when you hit send

   Follow one email from the send button to the inbox: the SMTP conversation in plain English, queues and retries, and the two gates every message faces.

2. 2
   Anatomy of an email: envelope, headers, and body

   Every email has two from addresses: the envelope one servers use and the header one you see. Learn the split that all email authentication depends on.

3. 3
   DNS for email senders

   Your entire email setup lives in DNS records, usually managed by people who don't know that. Zones, registrars vs DNS hosts, record types, and TTLs.

4. 4
   Who is who in email

   The email ecosystem mapped: mailbox providers, ESPs, corporate filters, blocklists, standards bodies, and who you can actually appeal to when things break.

5. 5
   The three fates of an email: inbox, spam, or rejected

   Rejected mail bounces loudly; spam-foldered mail says nothing. Your delivered rate can't tell inbox from spam, and the silent fate is where money leaks.

6. 6
   Email spoofing: why anyone can send as your domain

   SMTP never checks who a message is from. What spoofing and phishing do with that, and why every domain, even one that sends nothing, needs protection.

7. 7
   Checkpoint: how email actually works

   Prove the Part 1 model holds: a cumulative terminology drill, a three-step scenario, and a lab where you read your own domain's DNS records.

8. 8
   Part 1 exam: how email actually works

   Twelve questions across everything Part 1 taught. No feedback until the end: a score, a verdict, and the exact lessons to reread.

SPF, DKIM, and DMARC, taught record by record: what each one proves and how they fit together.

1. 9
   SPF explained: the list of who may send as your domain

   What SPF does, a real record read token by token, every mechanism and qualifier, and the two quiet failure modes that void a record without warning.

2. 10
   DKIM explained: the signature that travels with the message

   How DKIM signing works in plain English: selectors, the d= domain, key length rules, why ESPs use CNAMEs, and what a DKIM pass does and does not prove.

3. 11
   DMARC explained: your policy for mail that fails the checks

   The _dmarc record read tag by tag: how the pass verdict is computed, p=none to p=reject, the safe tightening path, and why bulk senders must publish one.

4. 12
   Alignment: why passing SPF and DKIM can still fail DMARC

   Relaxed vs strict alignment, worked header examples, the ESP trap that passes SPF and DKIM yet fails DMARC, and what a verified sending domain changes.

5. 13
   Reading DMARC reports

   DMARC aggregate reports show every server sending as your domain, judged by real receivers. What the XML means, and the weekly workflow that uses it.

6. 14
   Beyond the big three: MTA-STS, TLS-RPT, BIMI, and ARC

   The second shelf of email standards with honest weights: what each one does, who actually needs it, and why none of them decides whether you land in spam.

7. 15
   Checkpoint: authentication

   The Part 2 checkpoint: an eighteen-term drill, a chained diagnosis scenario, and a lab where you fix a real authentication finding on your own domain.

8. 16
   Part 2 exam: authentication

   The authentication exam: twelve questions on SPF, DKIM, DMARC, alignment and reports. Scored at the end, with a restudy list.

How mailbox providers decide who to trust: reputation, filtering, warming, and the dashboards that show you anything real.

1. 17
   Sender reputation: the score nobody will show you

   Sender reputation is a set of private scores mailbox providers keep on your domain and IPs. What moves them, why they drop fast, and where you can peek.

2. 18
   How spam filters decide where your email lands

   Spam filtering is a layered decision: acceptance at the SMTP door, machine-learned scoring, then per-user placement. What actually weighs, in order.

3. 19
   B2B email deliverability: when the receiver is a business, not Gmail

   Corporate gateways and Microsoft 365 quarantine judge B2B mail by admin policy, not engagement. Why selling to businesses is a different filtering game.

4. 20
   Shared vs dedicated IPs, and the truth about warming

   How shared IP pools work, the reputation you inherit from strangers, when a dedicated IP helps, when it hurts, and what IP warming honestly is.

5. 21
   The machine layer: reverse DNS, PTR records, HELO, and TLS

   PTR records, forward-confirmed reverse DNS, HELO names, and TLS: the checks receivers run on the sending machine, and why Gmail requires a valid PTR.

6. 22
   Blocklists explained: DNSBLs, Spamhaus, and getting delisted

   A blocklist is a DNS zone anyone can query. How DNSBLs work, what each Spamhaus list means, how you get listed, and which lists actually matter.

7. 23
   Engagement signals: what mailbox providers watch, and why open rates turned into noise

   Mailbox providers score what recipients do with your mail. Which signals still mean something, and why Apple's MPP turned open rates into noise.

8. 24
   Bounces, complaints and feedback loops

   SMTP reply codes in plain English, how bounces get classified, who sends complaint reports back to senders, and why suppression lists are non-negotiable.

9. 25
   The 2024 bulk sender rules from Gmail, Yahoo and Microsoft

   What Gmail and Yahoo require from bulk senders since February 2024, Microsoft's 2025 equivalent, and why the rules are the baseline for everyone.

10. 26
    Google Postmaster Tools and Microsoft SNDS: the dashboards providers actually give you

    Mailbox providers grade you in silence. Google Postmaster Tools and Microsoft SNDS are the exceptions: what each shows, and who is locked out.

11. 27
    Measuring deliverability: what you can and cannot know

    Your ESP's delivered rate means accepted, not inboxed. The honest instruments for measuring placement, and exactly where each one goes blind.

12. 28
    Checkpoint: reputation

    Prove the reputation part stuck: a cumulative term drill, a three-step scenario of complaint creep, and a lab that checks your domain against blocklists.

13. 29
    Part 3 exam: reputation

    Fourteen questions across the reputation part. Committed answers, a tiered verdict, and the lessons to revisit for every miss.

The sending craft: list quality, content, mail streams, and the habits that keep a reputation healthy.

1. 30
   List hygiene: the list is the reputation

   Your list is your reputation. Consent, bounce types, spam traps, sunset policies, and why bought lists end sending careers.

2. 31
   Email marketing laws: CAN-SPAM, GDPR/PECR and CASL at working level

   What CAN-SPAM, GDPR/PECR and CASL actually require, how one-click unsubscribe works, and what to verify before sending a single email for a client.

3. 32
   Content and design: what actually matters

   Spam-word lists are folklore, but filters do read your mail. Images, links, attachments, unsubscribe visibility and the plain-text part, sized honestly.

4. 33
   The Promotions tab is not spam: Gmail categories and Focused Inbox

   Mail in Gmail's Promotions tab was delivered and inboxed. What really drives tab placement, why escape hacks backfire, and when to stop caring.

5. 34
   Email sending volume: why consistency beats the big blast

   Filters read your sending rhythm. Why volume spikes hurt, the honest Black Friday playbook, and segmentation as a reputation tool.

6. 35
   Separate your mail streams

   On a shared domain your coldest mail prices your most important mail. Subdomain strategy, DMARC coverage, root protection, the lookalike trap.

7. 36
   ESP migration: switching email providers without losing deliverability

   The vendor-neutral cutover order: export suppressions first, authenticate before sending, overlap both paths, re-warm engaged-first, verify outside.

8. 37
   Checkpoint: sending well

   Prove the sending craft stuck: a cumulative term drill, a chained migration scenario, and a lab that audits your list practice against a checklist.

9. 38
   Part 4 exam: sending well

   The sending-craft exam: lists, law, content, tabs, patterns, streams and migrations, scored with a restudy list.

The part nobody else teaches: why correctly configured email quietly stops working, mechanism by mechanism.

1. 39
   What is deliverability decay?

   Deliverability decay is the slow, silent degradation of a correctly configured email setup. Where the drift comes from and why you never see it happen.

2. 40
   Why one-time fixes fail

   A deliverability fix is a snapshot of a moving system. The forces that undo it, their timelines, and why nobody in a small company owns email health.

3. 41
   How SPF records rot

   The five ways a working SPF record fails on its own: include-chain drift, lookup creep, second-record accidents, stale flattening, and migration wipes.

4. 42
   How DKIM breaks over time

   Why CNAME-delegated DKIM survives for years while pasted TXT keys rot: key rotation, account migrations, selector generations, and DNS cleanups.

5. 43
   How DMARC drifts

   DMARC rot is drift: policies that outlive the reality they matched, forgotten sp= and pct= tags, and report addresses that went dark years ago.

6. 44
   Decay you don't control

   Requirement waves, blocklist sweeps, shared-IP neighbors, silent filter changes, and aging lists: the decay you can't prevent, only detect early.

7. 45
   Monitoring for decay

   What to watch on a sending domain, how often to check it, and why the only trustworthy view of your email setup is the one receivers see.

8. 46
   Checkpoint: deliverability decay

   Prove the decay part stuck: a cumulative term drill, a year of silent rot in three decisions, and a lab where you write a monitoring plan for your domain.

9. 47
   Part 5 exam: deliverability decay

   Twelve questions on the decay mechanisms and monitoring. The verdict says whether the course core argument stuck.

From symptom to verified fix: reading the evidence, triaging, repairing in the right order.

1. 48
   The deliverability toolbox

   The free deliverability toolbox, job by job: DNS lookups, record checkers, blocklist and header tools, postmaster dashboards, and their blind spots.

2. 49
   Reading email headers

   How to open a message's raw source in Gmail, Outlook or Apple Mail, then read the Received chain and Authentication-Results like a professional.

3. 50
   Reading bounce messages: email bounce codes decoded

   The anatomy of a DSN, 4xx vs 5xx reply codes, enhanced status codes, greylisting, throttling, and the provider strings that name the exact problem.

4. 51
   Deliverability triage: the incident runbook

   The incident runbook: define the symptom, build the timeline, then work records, blocklists, reputation and content in that order.

5. 52
   Repairing a decayed setup

   The repair runbook in dependency order: inventory every sender, one SPF record, DKIM per sender, alignment, and only then DMARC. Then keep it fixed.

6. 53
   Verifying deliverability fixes from the outside

   Saving a DNS record proves nothing. Climb the verification ladder: authoritative queries, public resolvers, a real message's Authentication-Results.

7. 54
   Email blocklist removal: running a real delisting

   How to run a real blocklist delisting: fix the cause, work Spamhaus, Microsoft and Google the way they actually operate, and refuse pay-to-delist scams.

8. 55
   Checkpoint: the diagnosis capstone

   The capstone: diagnose a broken domain from a prepared case file and write up the findings the way a practitioner would.

9. 56
   Part 6 exam: diagnosis and repair

   The diagnosis exam: evidence questions on headers, bounces, triage, repair, verification and delisting, scored at the end.

Turning competence into work: audits, client communication, and what you can honestly promise.

1. 57
   How to run an email deliverability audit

   The repeatable email audit: intake, outside-in evidence, the client-access checklist, safe-change practice, and a findings write-up with priorities.

2. 58
   Explaining findings to a small business

   Every finding needs two sentences: what is true in plain English, and what it costs while unfixed. The translation craft that gets audits acted on.

3. 59
   Packaging deliverability services: audits, fixes, and retainers

   The three-service shape for deliverability work: fixed-scope audits, verified fix engagements, and monitoring retainers, priced with logic you can defend.

4. 60
   Email deliverability guarantees: what you can't promise

   Nobody can guarantee inbox placement. The promises a practitioner can actually keep, the ones nobody can, and the exact sentences that protect you.

5. 61
   Cold email deliverability: the honest answer

   Why cold email fights every reputation system by design, the truth about rotation networks and warm-up pools, the legal lines, and what to tell a client.

6. 62
   Client readiness: the gauntlet, part one

   Four client scenarios, twelve decisions: a vanished DNS zone, quarantined proposals, an imported gala list, a mid-season blocklisting. Play it honestly.

7. 63
   Client readiness: the gauntlet, part two

   Four harder client cases: a symptom that lies, a bought list, a problem that isn't deliverability at all, and a compound decay chain. The readiness exam.

8. 64
   Graduation: the competence checklist

   Sixteen self-assessable checklist items decide whether you can charge for this work, plus the sources that keep the rules from decaying under you.