How to prevent your emails from being tracked

All those nasty marketing emails that fill your inbox aren’t just promoting a product. They also control whether you opened the email, when you opened it and where you were at the moment, using software like MailChimp to incorporate tracking software into the message.

How it works? A single tracking pixel is embedded in the email, usually (but not always) hidden in an image or link. When the email is opened, the code inside the pixel sends the information back to the company’s server.

There have been some attempts to restrict the amount of information that can be transmitted in this way. For example, since 2014, Google has served all images through its own proxy servers, which can hide its location from at least some tracking applications. And extensions like Ugly Email and PixelBlock were developed to block crawlers in Chrome and Firefox.

There is also a simple basic step you can take to avoid crawlers: stop automatic loading of images in your email, as images are where most of these pixels are hidden. You won’t be able to avoid all the trackers that may be hidden in your email in this way, but you will stop many of them.

Here’s how to do it in top desktop and mobile email apps:

Disable automatic image upload in Gmail:

• Click on the gear icon in the upper right corner to access your settings and click on “View all settings”.
• On the “General” tab (the first), scroll down to “Images”.
• Select “Ask before displaying external images”.
• Scroll down to the bottom of the page and click “Save changes”.

Note that this will also disable Gmail’s dynamic email feature, which makes email more interactive.

Disable automatic image loading in Microsoft Outlook (Office 365):

• Click “File”> “Options”.
• In the “Outlook Options” window, select “Trust Center”.
• Click the “Trust Center Settings” button.
• Check the boxes labeled “Do not download images automatically in standard HTML messages or RSS items” and “Do not download images in encrypted or signed HTML email messages”. You can make several exceptions to the first item, if desired, by checking the boxes below it.

Disable automatic image loading in Apple Mail:

• Select “Mail”> “Preferences”.
• Click on the “Preview” tab.
• Deselect “Load remote content into messages”.

Disable automatic image upload in Gmail for Android:

• Touch the three lines in the upper left corner.
• Scroll down and select “Settings”.
• Touch the email account you want to work with.
• Scroll down and select “Images”.
• Touch “Ask before displaying external images”.

Disable automatic image upload in iOS Gmail:

• Open Gmail for iOS, touch the hamburger menu in the upper left corner and scroll down to the settings.
• Touch the account you want to customize and touch “Images”.
• Change from “Always display external images” to “Ask before displaying external images”.

Note that for anyone who wants to do this on the Gmail mobile client, it looks like it will only work for personal accounts and not for business accounts managed by G Suite, for now.

Disable automatic image upload in iOS Mail:

• Touch “Settings”> “Mail”.
• Find the “Messaging” section and disable “Load remote images”.

Another option is to use an email client like Thunderbird, which blocks remote images by default; the app allows you to download embedded content individually or allows photos of contacts you trust to not send hidden codes in your images.

July 3, 2019 update, 15:47 ET: This article has been updated to include additional information about email clients.

September 3, 2019, 7:35 pm ET update: This article has been updated to include instructions for disabling automatic image upload in Gmail for iOS.

Update on February 17, 2021, 17:30 ET: Microsoft Mail instructions have been removed and some instructions updated.