How to block Mailchimp open tracking in Gmail

Checked November 14, 2026. Written by the developer of Unseen, a free tracker blocker for Gmail.

Mailchimp is one of the most used newsletter services. Open tracking is on by default, so most Mailchimp newsletters you receive carry a tracking pixel.

What the sender sees

Through a tracking pixel, a tiny invisible image unique to you, the sender learns which subscribers opened each newsletter and when, used for open rates and to sort readers into groups. Gmail loads images through its own proxy, which hides your IP address, but the open is still recorded. More on what Gmail does and doesn't hide.

Check whether an email has it

In Gmail, open the email, click ⋮ and then Show original, copy the whole text and paste it into the email tracker checker. It lists every tracking pixel it finds and runs entirely in your browser.

Block it

With Unseen (free)

Unseen recognizes 4 Mailchimp tracking patterns, among 332 patterns from 184 companies, and also blocks hidden 1×1 images. It blocks only the tracker, so the rest of the email looks normal, and shows a note naming who tried to track you. It can only see Gmail, and it's open source.

Add Unseen to Chrome, free Also for Firefox

Without an extension

In Gmail's settings, set Images to Ask before displaying external images. That stops every tracking pixel, but also hides every normal picture until you click. Step-by-step guide.

Will the sender know I blocked it?

No. They see the same thing as when someone reads email with images off: no open is recorded.

Other tools: Mailtrack · HubSpot email tracking · Streak email tracking · Yesware · Mixmax · SendGrid open tracking · All 184 companies Unseen recognizes