MailPixel

You sent the email that mattered, and now you're wondering if anyone opened it. A tracking pixel is the usual answer: a tiny image hidden in the message, and when the recipient's mail app loads it, the server that hosts it logs the request.

MailPixel does exactly that, for free, in one step. You press a button and get an HTML snippet, the pixel's URL and a private activity link.

What sets it apart is how often it tells you not to trust the result too much. It's upfront that a request to the pixel is a signal, not proof that a person read the message. Mail apps and privacy features can load images automatically, or block them, so an open may be a machine and a missing open may still be a read.

No account is needed. Each pixel records requests for 30 days. The activity page shows each valid image request with a server timestamp, and whoever holds the private link can pause or delete the pixel. That link is the only key. According to the privacy page, the service stores only a hash of the management secret, so there's no account recovery and it can't send a replacement link.

The form asks for an optional private label and tells you not to put an email address or message content in it.

Pasting raw HTML into an email isn't something every mail app allows, so Gmail users are also pointed to a separate Chrome extension that adds tracking while you compose. The extension has its own listing.

The same privacy page says that when the pixel is requested, the service records the server time and a conservative client classification, and that it does not store the raw request IP address or the complete user-agent string in the pixel event table. That's less than many trackers collect.

It's still tracking someone who hasn't been told. Nothing on the site indicates recipients are notified, and in some places consent rules apply to this kind of pixel, so that's yours to check before using it on people who wouldn't expect it. The site names no person or company as its operator.

If you want a quick signal on an email and you're happy to treat it as a hint, MailPixel is an easy one to try.