In short. A tracking pixel is a tiny, usually invisible image in an email. When your email app loads it from the sender’s server, the sender learns that you opened the email, when, and roughly where you are [1, 2]. What helps: not loading images until you choose to, or an email app that loads them through its own servers. Where that stops: an image proxy hides your IP address, but the sender may still learn you opened the email [3]; clicking a link or replying still tells the sender your address is active [4].
How a tracking pixel works
An email can show images that aren’t inside the message itself: it holds only their addresses on the internet, and your email app downloads them when you view the email [1]. A tracking pixel is one of these images, one you can’t see [5]. The email was sent to you in particular, so loading its images can be linked straight back to your address [1].
When the image loads, the sender can learn [1]:
- each time you view the email;
- roughly where you are, from your IP address;
- which email app and platform you use;
- that your address is active.
Senders may also learn how many times you opened the email and whether you forwarded it [2]. Spam uses the same trick: once the image loads, the spammer knows your address is worth writing to [1, 4].
How to stop pixels from loading
There are two ways: don’t load images until you choose to, or let your email app load them through its own servers, so the request doesn’t come from your device. Here’s where each app keeps these settings.
Gmail. Gmail shows images automatically by default. To have it ask first, click Settings > See all settings, scroll down to Images, choose “Ask before displaying external images”, and click Save Changes [3].
Outlook. Classic Outlook for Windows doesn’t download pictures from the internet automatically by default, and Microsoft names avoiding tracking pixels as one of the reasons [5]. The setting is in File > Options > Trust Center > Trust Center Settings > Automatic Download [5]. Outlook.com loads external images through an image proxy: keep “Always use the Outlook service to load images” selected in your Privacy and data settings [6]. Outlook for iOS and Android has a Block external images setting [7].
Apple Mail. Protect Mail Activity downloads images in the background when an email arrives, whether or not you open it, and sends the requests through two separate relays, so senders don’t see your IP address [2]. On a Mac, it’s in Mail > Settings > Privacy; on an iPhone or iPad, in Settings > Apps > Mail > Privacy Protection [2].
Thunderbird. Thunderbird doesn’t load remote content by default: it shows a notification bar instead [1]. If you trust the sender, you can show images for a single message. Allowing a whole sender is weaker, because email addresses are easy to fake [1].
Some email apps can also show a message as plain text, which loads no images at all [4].
Where this stops
- Links and replies. Clicking a link in the email or replying to it confirms that your address is active [4].
- Showing images. When you choose to show images in an email, the pixel loads along with the rest of them [1].
- Proxies. An image proxy keeps your IP address from the sender, but the sender may still learn that you opened the email [3].
How Methmail will handle images
Images in emails will show right away, except in Spam. Our server will fetch them through its proxy when you open the email: the sender won’t learn your IP address or your device. We won’t load known tracking pixels at all.
The sender will be able to tell that the email was opened, and when: images will be fetched each time you open it. The proxy will see the image addresses, including in encrypted emails, and won’t record them. You’ll be able to turn off showing images right away in settings: then images will show only when you click a button.
More on the page Tracking in email: what Methmail will do about it.
Questions
Can you be tracked through email? Yes. An image that loads from the sender’s server can tell them when you opened an email, roughly where you are and which app you use [1]. Clicking a link or replying confirms that your address is active [4].
Is a tracking pixel the same as a read receipt? No, and Microsoft makes the same distinction [5]. A read receipt is a request: in Outlook, for example, you can decline to send one, and no one can force you to [8]. A pixel doesn’t ask: it loads with the images.
Does turning off images stop tracking? It stops pixels from loading until you show the images in an email [1]. Clicking a link or replying still confirms that your address is active [4].
What’s next
- Tracking in email: what Methmail will do about it
- How to unsubscribe from emails safely
- Email metadata: what it reveals about you
Sources
- Mozilla: Remote Content in Messages, Thunderbird Help, updated August 17, 2025. https://support.mozilla.org/en-US/kb/remote-content-in-messages
- Apple: Mail Privacy Protection & Privacy, December 12, 2025. https://www.apple.com/legal/privacy/data/en/mail-privacy-protection/
- Google: Turn images on or off in Gmail. https://support.google.com/mail/answer/145919?hl=en
- CISA: Reducing Spam, revised November 20, 2019. https://www.cisa.gov/news-events/news/reducing-spam
- Microsoft: Block or unblock automatic picture downloads in classic Outlook email messages. https://support.microsoft.com/en-us/outlook/block-or-unblock-automatic-picture-downloads-in-classic-outlook-email-messages
- Microsoft: External image protection in Outlook.com. https://support.microsoft.com/en-us/outlook/external-image-protection-in-outlook-com
- Microsoft: What is Block External Images in Settings? (Outlook for Android and iOS). https://support.microsoft.com/en-us/outlook/what-is-block-external-images-in-settings
- Microsoft: Add and request read receipts and delivery notifications in Outlook. https://support.microsoft.com/en-us/outlook/mail/add-and-request-read-receipts-and-delivery-notifications-in-outlook