Enveloper — HTML email editor for Gmail, Outlook & Yahoo

Write, lint, inline and preview HTML email, then drop it straight into a Gmail, Outlook or Yahoo compose window. Local-only.

Sending an HTML email from webmail usually means pasting markup somewhere, hoping it survives, and finding out it didn't when it lands in someone's inbox with the layout collapsed. Enveloper is the workbench that sits between writing the HTML and sending it. Open it from the toolbar and you get your source on one side and a live render on the other, framed the way it will appear in an inbox — subject line, sender avatar, and the snippet text a mail client will actually pull. Switch between a 640px desktop width and a 375px phone width, or flip to dark mode to see what forced inversion does to your palette. WHAT IT CHECKS Thirty-one rules, each reporting the line number, the clients affected, and the fix: Layout that silently collapses — flexbox, CSS grid, absolute and fixed positioning, floats, negative margins CSS that never resolves — custom properties, rem and viewport units, transforms, web fonts, external stylesheets Images that will not appear — base64 data URIs, plain-http sources, missing width attributes, missing alt text Elements mail clients strip — script, form, iframe, video, inline SVG Word-engine rendering quirks — background images without a bgcolor fallback, tables wider than 640px, links inside conditional comments that point somewhere the visible link doesn't Deliverability and structure — the 102KB point where messages get clipped and the unsubscribe link disappears with them, missing preheader text, missing charset, unclosed tags Click any line number to jump straight to it in the editor. WHAT IT FIXES Inline CSS moves your style rules onto the elements themselves, resolving specificity and !important the way a browser would, and leaves behind only what genuinely cannot be inlined — media queries, @font-face, :hover. That is the single most common reason an email looks right in a browser and wrong in a mail client. Tidy re-indents without touching the markup. The links panel lists every anchor with its anchor text, flags placeholders, staging hosts, plain http and unresolved merge tags, and tags every destination with UTM parameters in one pass — including hrefs buried inside conditional comments, which most tools miss. The plain-text tab generates a readable text/plain alternative with headings, bullets and URLs beside their anchor text. WHAT IT SENDS When it's ready, Insert into mail drops the HTML into your open compose window — replacing the body, or adding above or below what's already there. Because it targets whichever editable field you last clicked into, it also fills the signature and auto-reply boxes in your mail settings. If a field refuses the insert, Copy for paste puts rich HTML on the clipboard as a fallback that works anywhere. WHAT IT CAPTURES Open an email you received and press Capture to pull its HTML into the workbench. Clean capture then undoes what webmail did to it on the way in: it unwraps click-tracking redirect wrappers back to the real destination, strips tracking attributes, removes the namespace prefix added to every id and class, and drops the empty wrapper tags — while leaving styled spacers and anything holding an image alone. TEN TEMPLATES Newsletter, product announcement, two-column, event invite, order receipt, plain letter, two email signatures, a vacation responder, and an empty 600px shell. All table-based, all inline-styled, all passing the checks before you start.