Why "just attach it" does not work
HTML is the one common file type that looks like an attachment but behaves like a security risk. An .html file can contain a form that posts credentials somewhere, a script that redirects on open, or a pixel-perfect copy of a login page, so mail providers treat it the way they treat executables. Gmail rejects .html and .htm attachments at send time. Outlook and most corporate gateways either block them or strip them from the message before delivery. None of this is configurable from the sending side.
The actual path: link first, then email
Three steps, and the only one that changes anything is the first:
- Drop the .html file into LiveSend (drag-and-drop or paste the source) and copy the URL it returns.
- Write your email as normal.
- Paste the link into the body instead of attaching the file.
The recipient clicks a normal-looking link, gets a rendered page in their browser, and nothing was ever attached for a filter to inspect or block. Each view is logged, so you can also tell whether it was opened.
What still does not work
- Renaming the extension (.html to .txt, for example) breaks the file for the recipient without reliably fooling the filter, which usually inspects content, not just the extension.
- Zipping the file sometimes passes the filter, but shifts the burden to the recipient (extract, then open an unfamiliar file), which is worse for open rates than a link.
- Pasting the raw HTML as text in the email body gets sanitized or mangled by every major email client. It never renders as intended.
The short version
Do not attach the .html file. Host it (LiveSend takes under a minute for a one-off file), and send the link instead. It is the only path that reliably reaches the recipient as a working page rather than a blocked or broken attachment.
Not sure which host to use? See the shortest path from .html file to link.