Check your email's HTML before sending cold outreach.
Paste your email's raw HTML below to check text-to-HTML ratio, image and link counts, and tracking pixels before you hit send — the structural signals mail providers use to tell a genuine one-to-one message from bulk or template mail. Nothing is uploaded; it all runs in your browser.
Why check your HTML before sending cold email
Most HTML email checkers are built for marketing sends — they preview how a newsletter template renders in Gmail, Outlook, and mobile clients. Cold outreach has a different failure mode: the goal isn't rendering fidelity, it's looking like a genuine message from one person to another rather than a templated blast. Spam filters and recipients both pick up on the same structural tells — a low text-to-HTML ratio, several tracking links or a tracking pixel, and heavy inline styling all read as bulk mail, even when the copy itself is personalized.
Checking the raw HTML before you send catches issues a visual preview won't — a stray tracking pixel left in from a template, an image-to-text ratio that's drifted from a previous campaign, or link counts that are higher than they look on screen. Run it once when you build a sequence template, then again any time you change the email signature, add a logo, or copy in a section from a marketing template.
What counts as a good text-to-HTML ratio for cold email
Marketing-email guidance commonly points to a roughly 60% text / 40% markup and images split as a safe baseline for bulk sends. Cold outreach should lean further still toward plain text: a first-touch or follow-up email sent from a personal domain reads as genuine when it's mostly text with a signature, and reads as a campaign the moment it picks up a banner image, multiple buttons, or a footer full of social icons. If the checker flags a low ratio, the fix is usually to strip a signature image or logo, not to add more text.
The same logic applies to link counts. A personal email rarely contains more than one or two links; five or six — especially wrapped in redirect/tracking domains — is a pattern spam filters associate with mass mail. Run your subject line and body copy through the spam word checker at the same time, and check your sending domain's authentication with the free deliverability checker — HTML structure is one signal among several, and none of them fix a domain with no SPF/DKIM/DMARC or no warmup history. For the full setup, see our cold email setup guide, or see Warmerly plans if you want warmup and authentication monitoring automated instead of checked by hand.
How the checker works
Paste the raw HTML of an email and the tool parses it in your browser to measure the ratio of real text to markup, count images and links, and detect likely tracking pixels (tiny 1x1 images) and heavy inline styling — all signals mail providers use to distinguish a genuine 1:1 message from bulk or template mail. Nothing you paste leaves your browser; there's no upload and no signup.
Frequently asked questions
Where do I get my email's HTML source to paste in?
In Gmail, open the email, click the three-dot menu, and choose "Show original" — copy the HTML block from there. In Outlook, open the message in its own window and use Message → Actions → Other Actions → View Source (classic Outlook) or right-click → View Source in the web app. Paste the full HTML into the box above.
Why do images, links, and tracking pixels hurt cold email deliverability?
A cold email with lots of images, links, or heavy inline styling reads as bulk or marketing mail rather than a genuine one-to-one note, and that bulk-mail signal is one of the stronger ones spam filters weight. Tracking pixels — tiny 1x1 images used to detect opens — are increasingly flagged by Gmail and Outlook on their own, separate from the rest of the HTML.
What's a good text-to-HTML ratio for cold email?
Marketing-email guidance commonly recommends a text-heavy split, often cited around 60% text to 40% markup/images, to avoid looking like a bulk blast. For cold outreach specifically, aim even more text-heavy than that — a first-touch or follow-up email sent from a personal domain should look close to plain text with minimal formatting, not a templated newsletter.
Should cold email be HTML or plain text?
Plain text (or HTML that renders as plain text, with no images or heavy styling) is generally safer for cold outreach. It matches how a real person emails another person, and it avoids the image/link/tracking-pixel signals this checker flags. Save designed HTML templates for newsletters and marketing sends where recipients expect a branded layout.
How is this different from a marketing email HTML checker?
Tools like Litmus or a general HTML email tester are built to preview how a template renders across Gmail, Outlook, and mobile clients for a marketing send. This checker doesn't test rendering — it's built for cold outreach, scoring the structural signals (text-to-HTML ratio, image/link counts, tracking pixels) that make a one-to-one email look genuine instead of templated.
Is my email content stored anywhere?
No — the HTML is parsed entirely in your browser using the native DOMParser API. Nothing is sent to a server.
Want your sender reputation monitored too?
Warmerly checks SPF, DKIM, DMARC, and MX every day and automates warmup so cold email lands in the inbox instead of spam.