Your open rate is inflated by three machines - here is how to prove it

Yixiu Liu — Thu, 22 Oct 2026 12:09:52 +0000

If your cold email dashboard shows 50-70% opens, run this audit before you report it to anyone. Three machines fetch the tracking pixel on behalf of your recipient, and a naive counter calls all of them an "open".

1. Apple Mail Privacy Protection

Since iOS 15, Apple Mail pre-fetches remote images for users who enable MPP, whether or not the message is ever read. The fetch comes from Apple's proxy, so it looks like a normal image load.

2. Gmail's image proxy

Gmail rewrites image URLs through googleusercontent.com and fetches them itself. Two reliable tells:

A frozen user agent: Chrome/42.0.2311.135 ... Edge/12.246 - a browser combination that has not existed in years. It does not contain the string GoogleImageProxy, which is why classifiers that only look for that token miscount it.
Google egress ranges: 66.249., 66.102., 64.233., 209.85.

3. Corporate security scanners

Microsoft 365 with Defender, Barracuda, Mimecast, Proofpoint and friends detonate or rewrite every URL in an inbound message, images included. A scanner in Frankfurt "opens" your email before the recipient's laptop is awake.

The ten-minute audit

Export the raw events from your sending tool - not the summary, the per-event log with IP and user agent - then check four things:

Check	What a machine hit looks like
Repeated hits from one IP	Same IP loading the pixel 4-10 times within a minute
User agent	datacenter strings, the frozen Chrome 42 / Edge 12 pattern, `python-requests`
Timing	machine fetches land in a tight band right after send; humans spread across days
IP ownership	Google, Apple, Microsoft or a security vendor instead of a residential ISP

On our own sends the naive number was 61% and the human-only number was 34%. The click rate barely moved between the two definitions, which tells you which metric was real all along.

What to measure instead

Replies per 100 sends - a proxy cannot fake these
Human opens, defined explicitly and de-duplicated per recipient
Bounce and complaint rates for deliverability work

The uncomfortable part: honest tracking makes your numbers look worse than the competition's. If a vendor shows 60% where you measure 34%, the vendor is not better at email - it is counting prefetches.