Questions, answered without hedging.

The basics

What is MailSignals?

MailSignals is an email tracker for Gmail. A Chrome or Edge extension adds a tracking pixel and signed links to the mail you send, MailSignals records what happens to them, and a dashboard shows opens, clicks, replies and bounces with the reason behind every verdict. It asks for no access to your mailbox.

Who is it for?

Anyone who sends email that matters one message at a time from Gmail, in Chrome or Edge, and wants to know what happened to it: founders, freelancers, salespeople, recruiters, anyone waiting on a reply that decides something. It is not a mass-mailing tool, a CRM or an e-signature product, and it is not trying to become one.

Does MailSignals need access to my Gmail account?

No, and this is the thing that most separates it from every alternative. Sign-in asks Google for openid, email and profile only. There is no Gmail scope anywhere in the product, so nothing we run can read, send or delete your mail — not because we promise not to, but because we were never granted the ability. Everything Gmail-related happens inside the Gmail page in your own browser.

How do I get it?

Download the extension from the download page and add it to Chrome or Edge, which takes a couple of minutes; the page walks through it. Then sign in with Google, in the extension and on the dashboard, with the same account. MailSignals is in early access and open to anyone with a Google account. The extension is not on the Chrome Web Store yet, which is why it is installed from that page for now.

What does it cost?

It is free during early access, with every feature switched on and no limit on how much you track. Pricing will be announced before general availability, and early-access users will hear it first and directly, not by discovering a paywall.

Which browsers and mail clients does it work with?

The extension runs in Chrome and Edge on Gmail in the browser. Your recipients can use anything: the pixel and links work wherever images load and links are clicked, and the classifier recognises Gmail, Apple Mail, Outlook, Yahoo, Proton, Thunderbird and plain browsers, plus the proxies and scanners that sit in front of them.

Accuracy and what it can see

How accurate is open tracking?

Less accurate than any tracker's green tick implies, and MailSignals is built to say so. Gmail fetches images through a proxy and caches them, Apple Mail downloads them on delivery before anyone reads, and security gateways fetch everything. MailSignals classifies each request with one of 16 rules, records a confidence and a plain-English reason, and counts only what a person was plausibly behind. Replies beat clicks beat opens, and the interface says so.

Will it count my own opens when I look at my Sent folder?

On desktop Gmail with the extension installed, no. The extension tells the backend which sent messages you are looking at, and any pixel hit within 20 seconds of that is withdrawn as your own; a direct fetch from your own network with a Gmail referrer is recognised too. On a phone without the extension a proxied self-open cannot be told apart, so the dashboard offers "That open was me", and the fix that removes the ambiguity entirely is Gmail's "Ask before displaying external images" setting on every device.

What about Apple Mail Privacy Protection?

Apple's proxy downloads the pixel when the message is delivered, whether or not anyone reads it. MailSignals labels that "Delivered, open unconfirmed", shows an amber tick, and does not count it as an open at the default setting. You can choose to count it if you would rather treat delivery as a read.

Can it tell me which recipient of a group email opened it?

No, and it will not guess. One message carries one pixel, so an open on a multi-recipient message means someone read it. The tooltip says "N recipients, so we cannot tell which one", and per-contact statistics are only updated for messages with a single recipient. Trackers that do answer this rebuild your message into one message per recipient through the Gmail API, which is exactly the mailbox access MailSignals refuses.

Can it see if a recipient deleted, archived or reported my email?

No. Nothing leaves the recipient's mailbox when they do those things, so no tracker can observe them, whatever it claims. MailSignals reports the two recipient-side outcomes a sender can actually see: a delivery failure, from Gmail's own notice, and a reply.

How does it detect replies without Gmail access?

From the Gmail page itself. A thread that contains one of your tracked sends and gains a newer message from someone else is a reply; the extension notices it in the open thread and in the Inbox list. A reply to a thread you never open and that never appears in the Inbox can be missed, so "mark as replied" exists for that case. We would rather tell you about that limit than pretend it does not exist.

Privacy and recipients

What does it store about the people I email?

A timestamp, the user agent, the IP truncated to a /24 (IPv4) or /48 (IPv6) plus a salted hash of it, the referrer and the HTTP method. Never the full IP address, never a location, never the content of the email. Behind Gmail, Outlook.com, Yahoo and Apple the request comes from the provider's proxy anyway, so even the truncated network describes a data centre rather than a person.

Does MailSignals read or store my email?

For mail you send from Gmail in your browser, the body is never read, transmitted or stored: the extension adds a pixel and rewrites eligible links inside the page, on your machine. What we keep is the subject line, the recipients, the Gmail ids and the URLs of tracked links, so you can recognise the message. The one exception is that if you connect software that sends mail without a browser, that software sends the body to us to have the pixel added; it is rewritten in memory and not stored.

Are tracking pixels legal?

It depends where your recipients are. In the EU and UK the ePrivacy rules treat a pixel as access to the recipient's device, which needs consent, and France's CNIL now requires prior consent for marketing pixels. In the United States open tracking is lawful. MailSignals gives you the controls to comply: a do-not-track domain list, an optional disclosure footer, a per-message off switch, minimal retention and no location. You are the data controller for the mail you send.

Who else sees my data?

Two companies, both named in the privacy policy: Google, whose cloud MailSignals runs on (and whose Gmail and sign-in it depends on), and Resend, which delivers your digest email while you have it switched on and so sees what the digest contains. Nobody else. Your data is never sold, shared or used to train anything, and it is not passed to an analytics or advertising service. This website sets no cookies and loads no scripts either.

Can I export or delete everything?

Yes, yourself, without asking us. Messages, events, contacts and links export as CSV or JSON from the dashboard. "Delete everything" removes every message, event, link, contact, statistic and alert, and delete means deleted rather than flagged.

Using it

What do I need to start?

Chrome or Edge on a computer, a Gmail account, and the extension. Add the extension, sign it in with Google, and the next message you send is tracked; the dashboard uses the same sign-in. There is nothing to configure first, though the one setting worth changing is Gmail's images option, so your own reads are never counted as your recipient's.

What is t.mailsignals.io?

It is the host that serves tracking pixels and the redirects behind tracked links, and it serves nothing else. Keeping it separate from the app matters because a tracking host's reputation is shared with every recipient's spam filter, and the paths it uses are deliberately unremarkable rather than the words blocklists match on.

I have several Gmail accounts in one browser. Which ones are tracked?

Only the ones you link. The address you signed in with is linked automatically; any other Gmail account the extension sees is recorded as "needs a decision" and refused until you approve it. The server enforces this before anything is written, so mail from a colleague's account on a shared machine can never be filed under yours.

What happens to my email if MailSignals breaks?

It sends, unmodified, on time. The extension never cancels a send; every hook is wrapped so a failure leaves the message untouched, and anything that rewrites a body returns the original on any doubt. Losing the tracking on one message is always preferred to touching your correspondence.

Can it track email my AI agent sends?

Yes. Software that sends through the Gmail API never touches your browser, so no extension can see it. Instead the agent asks MailSignals to prepare the message: it gets the body back with the pixel and signed links added, sends it with its own Gmail access, and confirms the ids afterwards. A small server exposes this to any MCP client as five tools. The agent holds no signing key and makes no policy decision.