Email Preview Checker
Email ToolsPaste an HTML email and see what breaks in Outlook, Gmail, Apple Mail, Outlook.com and Yahoo — plus a deliverability and spam-trigger checklist.
The checklist and preview run in your browser. Your HTML is sent only when you sign in and ask for a test email or a rendered preview
A compatibility check, not a screenshot service: real cross-client renders need real installed email clients, which is the whole reason tools that offer them charge a monthly fee. This instead reads your email's HTML and CSS against real, sourced support data for five clients — including Outlook on Windows, which renders through Microsoft Word's engine and supports almost none of modern CSS — and flags what will actually break, before you send anything anywhere.
What people do next
Features
- Checks seven common causes of a broken layout — background images, rounded corners, flexbox, grid, positioning, custom fonts and video — against real per-client support data, not a guess.
- Flags missing image alt text and dimensions, which matter more in email than on the web: most corporate inboxes block images by default.
- A deliverability checklist: unsubscribe link, physical address, "view in browser", and Gmail's ~102KB clipping limit.
- A spam-trigger checklist — common phrases, shouting, excessive punctuation — clearly labelled as a checklist, not a prediction of where the email will land.
- Premium: real-client previews — the email drawn in Outlook 2007, 2010, 2013, 2016 and 2019, Outlook 365, Gmail, Apple Mail, iPhone, Android and more, each inside a window styled like that client, with download and "download all" options. A run takes a few minutes and fills in as each client finishes. Currently in demo mode: every picture is labelled "SIMULATED" on the image itself until a live vendor is connected.
- Send yourself a test email, then draw screenshots of exactly what was sent — free with the test, clearly labelled as a browser render rather than the real client.
- Add the real thing: upload a screenshot from your own Outlook or Gmail (free, no account), or capture it straight from your open inbox in one click when signed in.
- A grid of previews across phones (iPhone, iPad), webmail (Gmail, Outlook.com, Yahoo) and desktop (Outlook on Windows, Apple Mail), each laid out at that device's real width — approximations, clearly labelled as such, not screenshots from the clients.
- A simulated dark-mode preview, labelled as an approximation because no email client publishes its real auto-dark algorithm.
- The checklist and preview run entirely in your browser — nothing is uploaded unless you press "Email me a test" (which needs an account). Screenshots you upload or capture from your own mail client stay in your browser.
How to use the Email Preview Checker
- 1Paste your email's HTML, or load one of the sample emails to see how it works.
- 2Look across the grid of clients, click any card to enlarge it, and try the simulated dark-mode toggle.
- 3Choose Single client to look at one inbox at a desktop or mobile width.
- 4Select a client tab to see which of its issues are specific to that inbox.
- 5Work through the issues, starting with anything marked as breaking a client outright.
- 6Check the deliverability and spam-checklist sections before you send.
Frequently asked questions
Does this show me a real screenshot from Outlook or Gmail?
No — that needs the email actually rendered inside a real, installed copy of each client, which is genuinely expensive infrastructure and the reason tools that offer it charge a monthly fee starting well above what a free tool can absorb. This instead renders your HTML once, in your own browser, and separately reports what its CSS and structure are known not to support in each client — accurate about what will break, honest that it is not the pixel-for-pixel real thing.
Where does the compatibility data come from?
caniemail.com’s own published support tables (MIT licensed), for a deliberately small set of the features most likely to break a layout — not their full several-hundred-row table. Every check names its source.
Why does Outlook fail so much more than everything else?
Outlook on Windows does not use a browser engine to render HTML email — it uses Microsoft Word’s. That is why CSS backgrounds, rounded corners, flexbox and grid are unsupported there specifically, while Outlook.com — a different product, a real browser engine — supports most of them.
Is the dark-mode preview accurate?
It is a labelled approximation. No major email client publishes the algorithm it uses to automatically darken an email that has no dark-mode CSS of its own — what exists is community-tested, roughly-documented behaviour, and that is what this simulates. Treat it as a rough preview of the *kind* of problem dark mode can cause, not the exact result.
Will the spam-checklist score tell me if my email will reach the inbox?
No. Real spam-filter placement depends on sender reputation, domain authentication and recipient engagement — none of which is visible from a pasted HTML file. The checklist flags common, easily-fixed patterns (trigger phrases, shouting, excessive punctuation); it is a checklist, not a placement prediction.
Is my email content uploaded anywhere?
Not by the checklist or the grid. Parsing, checking and every preview run in your browser, and nothing about the HTML is sent anywhere. One optional button is different, and only sends it when you press it while signed in: "Email me a test" sends it to your own verified address through our email provider, Resend, and then the screenshots you ask for are drawn by our server from that same HTML. We store only that you made the request — a count, a size and a fingerprint used to check a screenshot matches what was sent — never the HTML or the pictures. A screenshot you upload or capture from your own mail client is never uploaded at all.