// Tool 003 · Email Compatibility
Audit email HTML before send.
Paste your email HTML. Get a categorized list of compatibility issues, structural problems, and missing essentials. Cross-client checks for Gmail, Apple Mail, Outlook (web, desktop, mobile), Yahoo, Yandex, AOL, Thunderbird, and webmail. Catches flexbox creep, missing alt text, 600px overflow, naked anchors, no preheader, Gmail clipping, and the usual offenders.
// 01
What gets checked
Layout (table-only, no flex/grid), 600px max width, inline-only CSS, alt text on every image, preheader text, bgcolor fallbacks for background images, anchor color overrides, DOCTYPE, charset, plus client-hostile properties (border-radius, box-shadow, gradients) that drop in older Outlook and several mobile clients.
// 02
Severity levels
Error: will visibly break in at least one major client (Gmail, Apple Mail, Outlook, Yahoo, Yandex, AOL). Warning: renders fine most places but risky in specific clients (Outlook 2007 to 2019, Gmail clipping over 102KB, certain mobile webmail). Info: heads-up, not a problem on its own.
// 03
Source-only audit
No rendering, no Litmus-style preview. Pure static analysis on the markup you paste. Use this as a pre-flight check before sending to a paid testing service or doing the manual screenshot dance across the major clients.