Email Template Checker That Tests Where Sends Actually Fail.

A complete template check covers two layers. The message layer: spam trigger words, broken links, malformed HTML, image-heavy layouts, and a missing plain-text part. The recipient layer: whether each address on the send list is real and live. The tool on this page lints the message layer, from size against Gmail's 102 KB clip to missing alt text, Outlook-unsafe CSS, and the unsubscribe link; the free email checker covers the recipient layer with 9 checks per address.

Run four passes. Paste the HTML into the checker above to catch size, alt text, and CSS issues. Scan the copy for trigger phrases with the spam check. Click-test every URL with the email link checker. Then verify the recipient list with the free email checker, because a clean template mailed to dead addresses still bounces. The whole loop takes minutes.

Filters score patterns, not single words, but the classic offenders are pushy money and urgency phrases: act now, limited time, 100% free, risk-free, no obligation, plus all-caps subject lines and stacked exclamation marks. One trigger rarely sinks a send. Several together, inside a heavy HTML template aimed at a stale list, usually do. The spam content checker scores your copy line by line.

Yes. Mail clients and filters penalize broken markup, image-only messages with thin text, and oversized payloads. Gmail clips messages above roughly 102 KB, hiding whatever sits below the fold, unsubscribe link included. Keep templates lean, balance images with real text, ship a plain-text part, and pair the HTML work with an address-level deliverability test on the list itself.

Because 20 to 40% of B2B email lists fail at catch-all domains, the check most free tools skip. Every hard bounce tells mailbox providers your hygiene is poor, and that reputation damage follows every future send regardless of template quality. The email verification engine resolves catch-alls with an AI-confidence pass, so you only mail addresses that can actually receive the template.

Yes. The template checker runs up to 30 checks an hour with no account, and the pre-send checklist is free forever. Recipient verification is free too: 4 addresses a day on the free email checker, or create a free account for 1,000 verifications, or 2,500 if you sign up with a work address. No card required, and paid credits never expire, with volume discounts on larger packs.

Every address gets the full check, catch-all domains included. The free email checker runs the identical 9-point engine as the paid API: syntax, domain and MX, SMTP handshake and mailbox ping, disposable and role detection, catch-all resolution with AI-confidence scoring, domain age, and SPF, DKIM, and DMARC authentication. Run the list there once your template passes the check on this page. The free tier caps volume, never accuracy.

Yes. Upload a CSV or call the API and bulk verification checks every address on the list. The free email validator handles bulk uploads on the same engine.

Your HTML is used only to run the check and show you the result. We never sell it. Our security overview covers how we protect your data, and the privacy policy spells out exactly what we touch and how it is used. Your template and your send list stay yours.

Yes. The REST API reference documents request and response shapes for every endpoint, so your campaign tool can verify recipients before each send. HubSpot, Salesforce, Zapier, Klaviyo, Mailchimp, and Brevo connect out of the box, and the native MCP server lets AI agents like Claude or Cursor run the check without glue code.