GUIDES · 26 · MIT LICENSED
Guides
Task-shaped, in the order you actually hit them. Where a guide explains a rule the product enforces — how a bounce is classified, what a segment compiles to, what a hundred thousand emails cost — the page imports the real function and shows you its real answer, rather than restating it in prose that would drift.
START HERE
Four guides, in order. At the end of them you have an instance you own, a domain that authenticates, and a delivered message.
- 1DeployBeginner · 9 minDeploy MailySend to your own Cloudflare accountOne click, about a minute, and the resources it creates in your account. What the deploy button actually provisions, and what it deliberately leaves for you.
- 2DeployBeginner · 8 minClaim a fresh instance and choose how you will sign inA newly deployed instance has no owner. Here is how the claim works, why it is time-limited, and which of the six sign-in doors to open.
- 3DeliverabilityBeginner · 10 minVerify a sending domain, and read the verification screen honestlyHow verification checks each record over DoH, what the four states mean, and why a domain can sit at pending for an hour without anything being wrong.
- 4SendingBeginner · 8 minSend your first emailFrom an API key to a delivered message, in curl and in code. Includes what to check when the response is a 200 and nothing arrives.
Deploy
4 guidesGetting an instance running, claimed, and pointed at a way to send.
DeployBeginner · 9 minDeploy MailySend to your own Cloudflare accountOne click, about a minute, and the resources it creates in your account. What the deploy button actually provisions, and what it deliberately leaves for you.DeployBeginner · 8 minClaim a fresh instance and choose how you will sign inA newly deployed instance has no owner. Here is how the claim works, why it is time-limited, and which of the six sign-in doors to open.DeployAdvanced · 14 minSelf-host MailySend on a plain Node serverThe same application, without Cloudflare in front of it: a Node build behind nginx, run under a process manager, with the platform bindings pointed somewhere else.DeployIntermediate · 12 minChoose a sending transport: Cloudflare, SES, Resend or SMTPFour transports with genuinely different ceilings and genuinely different event data. The real limits, straight out of the adapters, plus what failover does and does not buy you.
Deliverability
8 guidesThe part that decides whether any of the rest of it matters.
DeliverabilityBeginner · 13 minSPF, DKIM and DMARC, explained by the records you actually publishThe three records, what each one proves, and the exact values for your transport. Generated from the same code the setup screen uses, so the guide cannot drift from the product.DeliverabilityBeginner · 10 minVerify a sending domain, and read the verification screen honestlyHow verification checks each record over DoH, what the four states mean, and why a domain can sit at pending for an hour without anything being wrong.DeliverabilityAdvanced · 15 minMove DMARC from p=none to p=reject without losing mailA staged rollout with the percentage tag, what to look for in aggregate reports between stages, and the two sources of legitimate mail that always break first.DeliverabilityIntermediate · 14 minWhy your email goes to spam, in the order worth checkingA diagnostic order rather than a list of tips: authentication, then reputation, then list quality, then content. Includes a parser for the Authentication-Results header.DeliverabilityIntermediate · 11 minWarm up a new sending domainA schedule that starts with the people most likely to open, and how the send path learns an unpublished quota by watching rejections instead of guessing.DeliverabilityIntermediate · 11 minRead a bounce: eight classes, and what each one should do to your listPaste a real diagnostic and see how the product classifies it, including how long a soft bounce suppresses. Runs the actual classifier in your browser.DeliverabilityIntermediate · 9 minInbox placement is not delivery, and the difference is the whole gameWhy an SMTP 250 means accepted rather than inboxed, where real placement numbers come from, and how to read an estimate that is labelled as one.DeliverabilityAdvanced · 12 minOpen rates after Apple Mail Privacy ProtectionMPP pre-fetches every image, so a raw open rate measures nothing. How the privacy-adjusted rate is computed, which classification rules actually fire, and which are inert today.
Sending
3 guidesThe transactional path: one message, a batch, a template.
SendingBeginner · 8 minSend your first emailFrom an API key to a delivered message, in curl and in code. Includes what to check when the response is a 200 and nothing arrives.SendingIntermediate · 9 minBatch sends and scheduled sendsOne hundred messages per batch, partial success semantics, and scheduling — including how to reschedule or cancel a message while it is still queued.SendingIntermediate · 13 minTemplates: four engines, and which one you actually wantThe structured AST, handlebars, MJML and raw HTML — what each is for, why handlebars escapes triple braces identically to double, and where MJML cannot run.
Receiving
2 guidesInbound mail, and reading a rejection.
ReceivingIntermediate · 12 minReceive email: MX to mailbox, end to endThe full inbound path — MX records, Email Routing, the worker handler, the queue, and the mail screen — plus the one thing Cloudflare will not let the product read back.ReceivingIntermediate · 10 minDebug a 550 rejectionA 550 is a sentence, not a status code. How to read the enhanced code and the text, decide whether it is about you or the recipient, and what to do in each case.
Marketing
4 guidesSegments, broadcasts, automations and the exit link.
MarketingIntermediate · 14 minThe segment query language, and why it cannot be injectedThe full grammar with a live playground that runs the real parser and shows the real parameterised SQL. Twelve columns, no escape hatch, no string concatenation anywhere.MarketingAdvanced · 13 minBroadcasts at scale, without a counting passHow one campaign to a large audience is split across coordinators, why nothing counts the list first, and what makes the whole thing resumable after a crash.MarketingAdvanced · 12 minAutomations: instance mode or cohort modeTwo execution models with very different ceilings — 40,000 enrollments one way, 25,000 members the other — and a straight answer about which to pick.MarketingIntermediate · 10 minUnsubscribe done properly: RFC 8058 one-click and a preference centreWhat Gmail and Yahoo actually require, why the one-click endpoint returns plain text with no form, and how to offer preferences without hiding the exit.
Platform
5 guidesWebhooks, keys, agents, cost, and moving in.
PlatformIntermediate · 14 minWebhooks end to end: signing, retries and replayVerify a signature in six languages, understand the retry ladder, and know exactly when an endpoint gets disabled. Includes a live signature playground.PlatformBeginner · 9 minAPI keys, scopes and the test/live splitWhy the environment is visible in the key itself, what the two permission levels really allow, and how keys are stored so that a database dump yields nothing usable.PlatformAdvanced · 13 minGive an agent an inbox, safelyNine MCP tools, two of which will not act without a confirmation token — and the structural reason an agent cannot approve its own send.PlatformBeginner · 10 minWhat 100,000 emails a month actually costsEvery line item, priced, with a calculator that runs the same functions the pricing page uses. Includes what changes at 10,000 and at a million.PlatformIntermediate · 12 minMigrate from Resend without changing your codeChange the base URL and the key. Then the parts that are not one line: domains, webhooks, contacts, suppressions, and a cutover that can be rolled back.