Mailchimp, compiled
Mailchimp publishes the most complete openly licensed content style guide there is. It is written for people, like every guide of its kind. This page shows what it looks like once the machine-actionable parts are pulled out of it.
So this page does that, on somebody else's guide rather than a convenient invented one, and reports what would not convert as carefully as what would.
It sits under brand voice guidelines and the same compilation runs automatically when you answer the questions about your own voice.
What does Mailchimp's guide specify?
More mechanically than almost any other published guide. Its grammar and mechanics section is direct, and converts without argument.
| Rule | What the guide says |
|---|---|
| Serial comma | Use the serial comma, also known as the Oxford comma, when writing a list |
| Exclamation marks | Use them sparingly and never more than one at a time, and never in failure messages or alerts |
| Contractions | Encouraged (for a friendly tone) |
| Numbers | Spell out a number that begins a sentence, otherwise use the numeral, including ordinals. Numbers over three digits take commas |
| Ranges | A hyphen indicates a range or span of numbers and a period between times |
| Dates | Spell out the day and the month. Abbreviate only where space demands it |
| Times | Numerals with am or pm and a space between, and no minutes on the hour |
| Abbreviations | Spell out on first use where a reader might not recognise it |
| Ampersands | Do not use one unless it is part of a company or brand name |
| Emoji | Infrequently and deliberately |
| File extensions | All uppercase without a full stop, lowercase s to pluralise |
| Job titles | Capitalised for a specific role, lowercase for the role in general |
What do those become once compiled?
Almost all of them map straight onto a checker without interpretation. That is the test of whether a rule is really a rule: two people implementing it independently produce the same check.
| Rule | What a checker does with it |
|---|---|
| Serial comma | A consistency check across the document |
| Never more than one exclamation mark | A count within a scope, raised to an error in alerts |
| Ampersands | A pattern match with an exception list for brand names |
| Numbers over three digits take commas | A pattern match |
| Times formatted as numerals with am or pm | A pattern match |
| File extensions uppercase | A capitalisation check |
| Spell out abbreviations on first use | A conditional check: require the expansion before the short form |
| Contractions encouraged | Reportable but not enforceable, because encouraged is not a threshold |
Note the last row. “Encouraged” is the softest word in any style guide, and compilation starts to strain on it: you can count contractions, but the guide never says how many is enough, so any threshold would be ours rather than theirs.
Which checks these map onto covers the mechanics of that, and every download from this tool includes the same shape of file.
Which of its rules could not be compiled?
The honest half. These are real instructions, followed daily by the people who wrote them, and none of them survives conversion into a check.
- Tone that varies with the reader's state. The guide says tone should shift with how the reader is feeling, and no checker knows whether the person reading is delighted or locked out of their account.
- Writing for translation. The advice is sound and it is judgement: shorter sentences, fewer idioms, less compression. A checker can measure sentence length and cannot recognise an idiom.
- Writing about people. The guidance here is about care and accuracy, and getting it wrong is a matter of meaning rather than form.
- Accessibility guidance beyond the mechanical parts. Link text that makes sense out of context is checkable. Whether an explanation is actually clear is not.
- The word list, partly. Preferred spellings convert perfectly. The entries that say use this word carefully do not.
Neither the guide nor the compiling has failed. About a fifth of a good style guide is rules. The rest is context that makes the rules make sense. A model can act only on the rules.
What does compiling it reveal about the original?
Two things, and both are compliments.
First, how much of it is decided. Most published guides talk about personality and leave the mechanics implicit. This one commits, in writing, to the serial comma and to how a time is formatted. That is why it compiles at all.
Second, how much a guide relies on the reader being a person. The guide is at its best on how tone varies with context. It also resists conversion. That sums up the exercise: the parts a file cannot carry are named rather than pretended away.
Licence and attribution
The Mailchimp Content Style Guide is published by Mailchimp under a Creative Commons Attribution-NonCommercial 4.0 International licence, verified from the licence file in its own repository on 17 August 2026. The licence permits adaptation with credit and forbids commercial use.
This page is that adaptation and this is the credit. It carries no advertising: the article template on this site has no advertisement slot at all, which is what keeps the non-commercial condition true rather than merely claimed.
The rules above are quoted and summarised for the purpose of demonstrating compilation. If Mailchimp would rather this page did not exist, it comes down and the demonstration is rebuilt on the GOV.UK style guide, which carries no non-commercial condition.
Where these come from
Every claim above is quoted from one of these, and each was read on the date beside it. If one of them has changed since, the page is wrong and we would like to know.
- Mailchimp Content Style Guide checked 2026-08-17
- Mailchimp: grammar and mechanics checked 2026-08-17
- Mailchimp: voice and tone checked 2026-08-17
- The guide's source repository and licence checked 2026-08-17
- Creative Commons Attribution-NonCommercial 4.0 International checked 2026-08-17
That was somebody else's guide. For yours, spend a few minutes on the questions and get the compiled version.
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