A new, $30-per-month email service allows email senders to track whether their emails have been opened, the physical location where they were opened, and how many times they were opened. Tracking emails with this feature or other third-party plugins are unethical, invasive, and no one should do it.

The service is called “Superhuman,” and, as Mike Davidson, Twitter’s former vice president of design wrote in a now-viral blog post, nonconsensual read receipts in email are a form of surveillance that should worry everyone. Superhuman does not specifically explain how its technology works, but it likely uses a “tracking pixel,” a common way of tracking whether emails were opened and some basic information about the operating system used to open it.

A tracking pixel is exactly what it sounds like: A tiny, pixel-sized (usually invisible) image that is sent in the body of an email but is hosted elsewhere, on a third-party server. When that pixel is loaded from the remote server, the person who embedded it can be sure that the email was actually opened, where (using the IP address of the computer to approximate), and on what kind of operating system. Read receipts are opted into by the person receiving the email; tracking pixels (secretly) make that choice for the person receiving the email.

There are lots of services that offer this (but Superhuman offers it built-into the service, by default.) Superhuman did not respond to a request for comment for this article.

Tracking pixels are how newsletters and email marketers can tell whether their emails have been opened. That use, by large corporations, is actually the rare form of corporate surveillance that is less dystopian and invasive than its use by private citizens; letting J. Crew know whether its subject line for a summer sale was effective is far less invasive than being spied on by your friend and called out if you mention you didn’t see their email.

There’s an endless well of content about how to deal with email, the interpersonal politics of read receipts, work-life balance, and so-on, but few of those articles grapple with what the advent of tracking pixels means for society, interpersonal relationships, and work. It is the end of boundaries and the normalization of nonconsensual personal surveillance.

As someone who has a job that relies heavily on interpersonal digital communication (Slack, Email, and Twitter DM), the rise of tracking pixels is a personal nightmare. My life is a series of choices about how to prioritize these communications, and how to prioritize my life outside of work. About a year ago, I turned off almost all notifications on my phone because, while I work a lot, I had one-too-many angry Twitter mentions or DMs interrupt a personal dinner or time with friends and family. My thinking was that if I didn't see something immediately, I had plausible deniability if I didn't respond to a DM right away.

I have seen and read emails that I intended to eventually respond to, for example, while I was drunk at a bar, lying in an emergency room bed, at a funeral, at my mom’s birthday party, while stopped at a red light on my bike, etc. Sometimes I have responded to those emails right away; other times it’s taken me weeks. Sometimes I haven’t ended up responding at all. Not responding immediately to those emails doesn’t make me a bad person.

There are different brain spaces required to reply to different types of emails and messages. Shitposting on Twitter at a bar is significantly different from thoughtfully responding to a work-related Twitter DM or sending a difficult email or delivering bad news. Sending a quick text to someone you talk to every day is different from trying to catch up with a friend you haven’t spoken to in months. Email tracking (or Twitter stalking, etc) treats all emails the same—if an email has been read but not responded to, well, the person is ignoring you. This is an unhealthy way to think!