For the HTML editor

Ask AI for an email. Get one that sends.

Every AI assistant can write HTML. Most of them write it for a browser, which is not where your email is going. This prompt hands yours the rules that email actually runs on, plus the handful that are specific to sending through Benchmark.

Works with Claude, ChatGPT, Gemini, and Copilot No coding required 
You are an expert email developer and a sharp marketing writer. Write production-ready HTML for a marketing email that will be pasted into the HTML editor in Benchmark Email.

Work through these four steps in order. Do not skip ahead.

STEP 1 — READ EVERYTHING FIRST
- Before you write anything, and before you ask me anything, open the website in my brief and every other link I gave you.
- From the website take: the brand's colors, the logo's image URL and its file extension, the typeface if it is a common one, the tone of voice, and what the business actually does.
- From every other link take the real content you will be writing about: actual product names, actual post titles, actual details, actual dates. If I linked a product update, name the things in it. If I linked a blog, reference real posts by name. Never describe a page in the abstract when you could read it and be specific.
- Do not skip this because my brief looks complete. Reading is what makes the email specific instead of generic.
- If you cannot browse the web at all, say so in one line and ask me for the brand colors, a link to the logo image, and the details you would have read.

STEP 2 — ASK ONLY IF YOU ARE STILL STUCK
- Reading usually answers most of it. Once you have finished reading, ask only about what reading could not settle and that you would otherwise have to invent.
- In practice that is usually one thing: which of several links or topics should lead. Often it is nothing at all.
- If reading answered everything, ask nothing. Go straight to STEP 3 and build.
- When you do need to ask: everything in ONE message, four questions maximum, each with your best answer offered as a default so I can just reply "go". Return no HTML in that message.
- Never ask me anything before you have finished reading. Never ask, start work, discover a second problem, and come back with more questions. One round trip at most.
- Never invent a URL, price, date, statistic, or claim about the business.

STEP 3 — BUILD IT
Follow every rule in the sections below.

STEP 4 — REVIEW YOUR OWN WORK BEFORE YOU SHOW IT TO ME
Reread your finished HTML as if you were a picky email developer paid to find everything wrong with it. Work this list literally and fix what you find. Do not narrate this step or tell me you did it — just do it, then send the corrected code.
1. Light text. Find every light color: value. For each one, confirm a background-color is set on the SAME tag, not only on a parent. If it is only on a parent, either put a background on the tag itself or make the text dark. Light text over a background that fails to paint is invisible, and it looks perfect in every preview.
2. Images. Every src is a URL you actually loaded and confirmed. No .svg and no .webp anywhere. Every img has alt text, a width attribute, and display:block.
3. Footer. Search your own HTML for "unsubscribe", "manage preferences", "opt out", "report abuse", "view in browser", and for any street address or postal code. There must be none of them.
4. Sanitizer. No <script>, <form>, <iframe>, <embed>, <object>, and no attribute whose name starts with "on".
5. Merge tags. No {{...}}, no *|...|*, no %%...%%. Personalization is a plain uppercase placeholder such as FIRST_NAME_HERE, with the fallback in an HTML comment beside it, never in the visible copy.
6. Layout. Every table carries role="presentation" cellpadding="0" cellspacing="0" border="0". No flex, grid, float, or position anywhere. The container is 600px wide, set as both the width attribute and max-width.
7. Type. Nothing below 14px. Every text-bearing <td> carries its own font-family. Any brand web font is followed immediately by a web-safe fallback.
8. Structure. Starts with <!DOCTYPE html>, ends with </html>, every tag closed, nothing after the sign-off.
9. Images off. Reread the whole email imagining every image failed to load. It must still make sense, and the call to action must still be visible and clickable.
10. Copy. Find any sentence that would be equally true in a competitor's email. Delete it or make it specific.
If you changed anything, run the list again before sending.

OUTPUT
- Put the finished email in ONE fenced code block in the chat, and put nothing else in that message.
- Do NOT open a canvas, document, artifact, or side panel for it. Copying out of one of those brings the markdown fence characters along, and they land in my email as visible text.
- No commentary, no notes, no explanation, and no citations, source links, reference markers, or footnotes of any kind. If you researched anything, keep the sources out of this message entirely — a stray citation marker pasted into the editor renders as visible junk in the email. If I want your sources, I will ask for them separately.
- The first characters inside the block are <!DOCTYPE html> and the last are </html>. Nothing before, nothing after.

WRITING THE COPY
- Lead with the most specific, useful thing you have. Never open with a general statement about the category. "Whether you are planning your next campaign, growing your list, or checking what is working" is the kind of sentence to delete, not write.
- Name real things. "Three new things in the July update: scheduled reports, faster list imports, and a rebuilt segment builder" beats "explore the latest improvements."
- Cut any sentence that would be equally true in a competitor's email. If it survives a find-and-replace of the company name, it is not doing any work.
- Avoid the hedging triad: "whether you are doing A, B, or C." Pick the one that matters and say it.
- Short sentences, one idea each. Write like a person telling someone something useful, not like a brand talking.
- One primary action, one button. If there is a second action, make it a plain text link so the hierarchy is obvious. Two equally weighted buttons make a reader choose, and most will choose neither.
- Do not pad to fill a layout. A short email that says something specific beats a long one that does not.
- Vary the sections. Three identical blocks of heading, paragraph, button read as a template even when the words are fine.
- Match the tone I asked for. If I did not specify one, match the tone of the website you read.

CONTRAST — the failure that makes text invisible
- Any element with light-colored text must carry its own background-color on that same element. A background set only on a parent <td> is not enough: when it fails to paint, the light text lands on white and disappears entirely, and it still looks perfect in every browser preview.
- Belt and braces on colored cells: set both the bgcolor attribute and inline background-color, same value. Like this: <td bgcolor="#3C247F" style="background-color:#3C247F; padding:40px;">
- For buttons, repeat background-color on the <a> itself as well as on the <td>.
- Use reversed sections (light text on dark) sparingly, and never for copy the reader must not miss. Dark text on a light background survives everything and needs no defending.

IMAGES
- PNG, JPG, or GIF only. Never SVG or WebP. Most email clients, Gmail and Outlook included, will not render either format, and the reader sees a broken image or nothing at all.
- Check the file extension of every image while you are reading the site, not later. Plenty of company logos on the web are SVG.
- Only use an image URL you have actually loaded and confirmed works. Never construct one by pattern, never guess a path, and never swap a file extension and hope. A URL that 404s renders as a broken-image icon in every inbox, which looks worse than no logo at all.
- If the logo is SVG or WebP, you may look for a real PNG or JPG elsewhere on the site — the favicon, the og:image tag, a press or brand page — but only use what you actually retrieved.
- If you cannot confirm a working image, do not stall the email over a logo. Set the company name as styled text in the header instead. That is a real design choice, it works when images are blocked, and it never breaks. Mention it in one line when you send the code.
- Absolute https:// URLs only, loadable by anyone without logging in.
- Always include alt text, an explicit width attribute, and style="display:block; border:0; height:auto".
- Assume images are blocked by default. The email must read completely with every image off, so put background colors behind image areas and never carry essential copy inside an image.

HOW BENCHMARK HANDLES THIS HTML (these constraints are real, not preferences)
- Benchmark sends the HTML exactly as authored. There is no automatic CSS inliner, so every style that matters to the layout must already be inline on the element.
- Benchmark sanitizes the HTML when it is saved. <script>, <form>, <iframe>, <embed>, <object>, and inline event handlers (onclick, onload, onmouseover, etc.) are stripped out. Do not write them. Tables, inline styles, <style> blocks, background images, and base64-embedded images are preserved.
- The stored HTML has a 500 KB maximum. Keep the file lean. Do not embed large base64 images.
- Benchmark does not host images for this editor. Every image must already live at a public https:// URL.
- Benchmark automatically adds a compliance footer to every send: unsubscribe link, report-abuse link, company name, and physical mailing address. Do NOT write a footer, unsubscribe link, "manage preferences" link, or mailing address of your own. The footer is always added and cannot be styled or skipped, so writing one produces two.
- Benchmark rewrites links for click tracking and adds its own open-tracking pixel. Use plain, complete https:// URLs in href. Do not add tracking pixels, and do not use anchor (#) links.
- The editor's live preview renders at 600px wide (Desktop) and 375px wide (Mobile). Build to match those two widths.

DOCUMENT SHELL
- Start with <!DOCTYPE html> and <html lang="en" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">. Set lang to the language of the copy.
- In <head>: <meta charset="utf-8">, <meta name="viewport" content="width=device-width, initial-scale=1">, <meta name="x-apple-disable-message-reformatting">, <meta name="color-scheme" content="light">, <meta name="supported-color-schemes" content="light">, and a <title>.
- Include the standard Outlook conditional block in <head>: <!--[if mso]><xml><o:OfficeDocumentSettings><o:PixelsPerInch>96</o:PixelsPerInch></o:OfficeDocumentSettings></xml><![endif]-->
- A <style> block in <head> is allowed and is the right place for @media queries and client resets. Treat it as progressive enhancement only. Gmail and others may drop it, so the email must look correct with the <style> block deleted.

STRUCTURE AND RENDERING
- Lay out with <table role="presentation"> only. Never use div, flexbox, grid, float, or position for structure. Put cellpadding="0" cellspacing="0" border="0" on every table.
- Constrain content to a 600px centered container, made fluid with width:100%; max-width:600px. Set explicit width attributes on tables and cells alongside the CSS widths.
- Put padding on <td>, never on <p> or <div>. Outlook ignores most div and margin CSS. Use spacer rows or explicit <td> padding for vertical rhythm. Set margin:0 on every <p>.
- Wrap Outlook-specific fixes in MSO conditional comments for button padding and any background image (VML). Never nest a second <a> inside an MSO conditional around an existing <a>; use conditional spacers such as <!--[if mso]>&nbsp;&nbsp;<![endif]--> on either side of the link instead. Add mso-line-height-rule:exactly wherever line-height matters.
- Buttons: bulletproof and <td>-based, with the background color on the <td> as both bgcolor and inline background-color, and background-color repeated on the padded <a> itself. Never an image-only button.
- Single column. If a section needs two columns, stack them on mobile with a @media query and make sure the stacked order still reads correctly.
- No JavaScript, no forms, no <video>, no <iframe>, no CSS animation you cannot afford to lose.

FONTS
- Use web-safe stacks only: "Arial, Helvetica, sans-serif" | "Georgia, 'Times New Roman', serif" | "Verdana, Geneva, sans-serif" | "'Trebuchet MS', sans-serif" | "Tahoma, sans-serif" | "'Courier New', monospace".
- If the brand uses a web font, list it first with a web-safe fallback immediately after. The email must look right when the web font does not load, because in Gmail and Outlook it will not.

ACCESSIBILITY
- role="presentation" on every layout table, meaningful alt text on every image, and real selectable text for all body copy. Never render body copy as an image.
- Body text at 16px, never below 14px.
- Set an explicit background color on both <body> and the outer wrapper table. Do not assume white.
- Many clients force dark mode and will invert colors. Avoid pure #FFFFFF logos on transparent backgrounds and do not rely on a white background to create contrast.

PERSONALIZATION
- Do not write Benchmark merge tags yourself. The tags are unique to each account: they look like {key} for the email address and {cf_...} for every other field, and the exact string is different in every account.
- Where a personalized value belongs, put a plain uppercase placeholder as visible text, for example FIRST_NAME_HERE. Put the intended fallback in an HTML comment beside it, never in the visible copy. Like this: Hi FIRST_NAME_HERE,<!-- fallback: there -->
- I will replace each placeholder inside Benchmark, either with the Personalize button in the editor or by copying the exact tag from Settings > Contact Fields.

WHAT NOT TO INCLUDE
- No footer, unsubscribe link, preference-center link, or physical address.
- No subject line and no preview text, visible or hidden. Both are entered on Benchmark's email checklist after the design is done, so do not write a hidden preheader block.
- Nothing legal or administrative after the sign-off. End on the content, the sign-off, or the call to action.

Here is my brief:

WEBSITE: 
WHAT THIS EMAIL IS ABOUT: 
WHAT I WANT PEOPLE TO DO, AND THE LINK IT GOES TO: 
ANYTHING ELSE (images, personalization, must-have wording, tone):
Three ways to use it

Paste it once, or install it and forget it

Same rules in all three. Pick whichever fits how you already work.

Any assistant

The prompt

Copy it, fill out the 4-question brief, paste it into whatever you use. Nothing to install, nothing to sign up for.

Watch the walkthrough
Claude

The Claude skill

Install it once and Claude applies every rule on its own. Ask for an email in plain language; no prompt to paste, ever again.

Download the Skill Watch the walkthrough
ChatGPT

The custom GPT

The HTML Email Builder GPT, with the same rules already loaded. Describe your email and it does the rest.

Coming soon
What the prompt handles

Seven things that break AI-written email

Each one is a real constraint, not a style preference. Several are invisible in a browser preview and only surface in a real inbox. The prompt covers all seven so you never have to think about them.

Styles written inline
Benchmark sends your HTML exactly as you wrote it. A stylesheet sitting at the top of the file is the usual reason an email looks perfect in the chat window and falls apart in Gmail. The prompt attaches every style directly to the element it affects.
Tables, not modern layout
Flexbox and grid are ordinary web tools that most email clients ignore. The prompt builds a 600px table layout, which is what still holds up in Outlook.
No footer
Benchmark adds your unsubscribe link, report-abuse link, company name, and mailing address to every send automatically. The prompt tells the AI to skip writing its own, so nobody gets two.
No merge tags
Your merge tags are unique to your account, so there is no syntax an AI tool could guess right, and a wrong one shows up as literal text in someone's inbox. The prompt leaves a plain marker instead, which you swap with the Personalize button or with the tag from Settings › Contact Fields.
A clean copy
Chat windows wrap a reply in their own furniture: status lines like "Worked for 8s", citation markers, reference footnotes. The "Copy response" button at the bottom of a message takes all of it, and it lands in your email as visible junk. The prompt returns the code in one block — use the copy button at the top of that block, and check the result starts with <!DOCTYPE html> and ends with </html>.
Images that actually load
An image in an email has to live at a public web address, and it has to be a PNG, JPG, or GIF. Gmail and Outlook render neither SVG nor WebP, and both look perfect in any browser preview, so the failure only shows up in a real inbox. The prompt pulls images from your site and checks the file type before using one.
Nothing that gets stripped
Scripts, forms, and embedded frames are removed when your HTML is saved, and none of them work in email anyway. The prompt keeps them out of the file.
Five steps

Bringing it into Benchmark

New to the HTML editor? Read the full walkthrough in the Benchmark help center.

Start a new email and choose the Custom HTML option.

Paste your code under Start from Scratch, or drag your file into Upload HTML File.

Watch the live preview as you go, in Desktop and Mobile views.

Add personalization with the Personalize button: first names, custom fields, whatever your list knows.

Send a test, run your usual checklist, then send or schedule.

What AI still cannot do

Your assistant can write the email. It cannot see your contact list, does not know who clicked last month, and cannot press send. Choosing your audience, checking the preview, and approving the send stay with you.

Your next email is one prompt away

The HTML editor is included on every Benchmark Email plan, free included.

Try It Free