Does open tracking hurt cold email deliverability?
It can, and for cold email the data it gives you is too unreliable to justify the risk. Google's sender guidelines don't mention tracking pixels at all. On opens, they say Google doesn't track open rates. They add that low open rates aren't necessarily an accurate sign of deliverability or spam problems.
The warnings come from the cold email tools themselves, the same companies that sell open tracking:
- Snov.io. Its knowledge base article on open tracking, published 9 October 2026, says: "Spam filters can treat that image as a sign of bulk email." It adds that its analysis of thousands of user campaigns shows emails without open tracking can get up to twice as many replies. That is Snov.io's own data, with no method published on the page. Open tracking is off by default in new Snov.io campaigns.
- Instantly. Its Academy lesson on campaign analytics says Instantly recommends turning off open tracking because it can hurt deliverability and isn't a particularly useful metric. Its open tracking help page describes a Delivery Optimization setting that disables open tracking to improve deliverability.
- Hunter. Its cold email guide (September 2023, updated April 2026) is more cautious: some cold email experts believe tracking lowers deliverability, partly because a pixel forces you to send HTML.
For a founder sending a few hundred cold emails a week, turn it off unless a step in your sequence depends on it.
What does open tracking add to your email?
Tracking adds four things to a message that a normal one-to-one email doesn't have; the last applies only if click tracking is on. Each is something a spam filter can look at.
| What tracking adds | What it changes | Who says it matters |
|---|---|---|
| A tiny invisible image (the pixel) | The email must be HTML, not plain text | Hunter |
| A second domain that hosts the pixel | Filters check that domain's reputation too | Hunter's guide to custom tracking domains |
| A shared default tracking domain | Other users of the same tool affect that reputation | Hunter; Snov.io |
| Rewritten links (if click tracking is on) | Every link points to a tracking server first | Snov.io |
The shared domain is the part most founders miss. Hunter's guide to custom tracking domains (September 2023) explains that spam filters check the reputation of every domain in a message, including the one hosting the pixel. On a tool's default domain, you lose control of that reputation, and if other users damage it, your deliverability suffers with theirs.
A custom tracking domain, a subdomain such as track.yourdomain.com, fixes the sharing problem. It doesn't remove the pixel. Snov.io's article says a warmed-up custom tracking domain lowers the risk, but tracked emails can still land in spam more often than untracked ones.
Why are open rates wrong even when emails arrive?
An open is recorded when the pixel image loads. Apple Mail, Gmail and Outlook, the top three clients in Litmus's data, each now control when that happens, so the number tells you more about your list's email apps than about readers.
- Apple Mail. Apple's Mail Privacy Protection page says the feature hides the reader's IP address and prevents senders from seeing whether the email was opened. Apple announced it in June 2021 as stopping senders from using invisible pixels to collect information. Apple notes that it does not extend to links or attachments.
- Gmail. Google's Workspace admin help says Gmail uses Google's secure proxy servers to serve images in messages, so the pixel loads from Google's servers.
- Outlook. Microsoft's support page for classic Outlook says Outlook is configured by default to block automatic picture downloads, and lists avoiding tracking pixels as one reason. A reader who never clicks Download Pictures never counts as an open.
The scale shows in Litmus's email client report: of more than 1.5 billion opens it tracked in September 2026, it attributed 76.56% to Apple and 16.10% to Gmail. Litmus says opens from Mail Privacy Protection users are not considered reliable opens. Your own list may have a very different mix, which is exactly why the number moves.
Two more effects push the same way. Mailchimp's help page on open and click rates warns that bot activity such as Apple's Mail Privacy Protection can falsely inflate open and click metrics. And Instantly's troubleshooting page notes that opens won't register if the email is in the spam folder, so a low number can mean spam, blocked images or simply readers on Outlook.
A worked example: same email, two open rates
Here is what the client mix alone does to your open rate. The inputs are made up for illustration; the arithmetic is ours. Assume about a third of people in every group actually read the email, every Apple Mail inbox with Mail Privacy Protection registers an open (the inflation Mailchimp warns about), and one in ten Outlook readers clicks Download Pictures.
| List A (startup-heavy) | List B (enterprise-heavy) | |
|---|---|---|
| Delivered | 200 | 200 |
| Apple Mail / Gmail / classic Outlook | 50 / 90 / 60 | 20 / 60 / 120 |
| People who actually read it | 15 + 30 + 20 = 65 (32.5%) | 7 + 20 + 40 = 67 (33.5%) |
| Opens recorded | 50 + 30 + 2 = 82 | 20 + 20 + 4 = 44 |
| Reported open rate | 41% | 22% |
Real reading is almost the same on both lists, yet the dashboard shows 41% against 22%. If you rewrote your subject line between these two sends, you would credit or blame the wrong thing. Security scanners that load images before a person sees the message, which Snov.io describes, would push both numbers up again.
This is the pattern in one February 2026 r/coldemail thread: a B2B sender emailing about 1,000 pharma and healthcare contacts, more than half of them existing customers, reported opens falling from about 25% to 15% and asked whether it was deliverability or fatigue. Commenters offered at least five different causes, from stale data and audience fatigue to Microsoft filtering, because the open rate alone can't separate them.
What do cold emailers on Reddit report?
Across three r/coldemail threads from February to April 2026, most commenters who discussed opens had stopped trusting them, but they disagreed about whether the pixel itself hurts placement.
- Opens are noise. In an April 2026 thread asking who still tracks opens (about 33 comments when checked on 24 October 2026), several replies named Apple's privacy feature or Gmail's image caching as reasons they now judge campaigns by replies.
- The pixel may not be the main problem. One commenter in that thread argued: "The pixels themselves aren't what's tanking inbox placement, it's usually the ESP infrastructure or domain reputation behind them." The same person said a tracking domain with a bad reputation can hurt.
- Small reported gains. Two commenters in two different threads, including a March 2026 thread titled Stop Tracking Open Rates, each said reply rates rose about 0.4% after they turned tracking off. Neither gave a sample size, so treat it as two anecdotes.
- Test placement directly. Several commenters suggested a placement test instead; one described sending each campaign to their own inboxes at Gmail, Outlook and Yahoo to see where mail lands, which answers the question opens were meant to answer.
A practical point from the February thread: one commenter noted that corporate email gateways can rewrite tracked links, so click numbers from large companies can be wrong too.
What should you measure instead of opens?
Measure what a person does on purpose: replies, positive replies and booked calls. Then check deliverability with tools built for it.
| Metric | What it tells you | Where the number comes from |
|---|---|---|
| Replies per person contacted | Whether the list and message work | Your inbox; count people, not emails |
| Positive replies | Whether the offer interests anyone | Tag each reply: interested, not now, no, remove me |
| Calls booked | Whether replies turn into pipeline | Your calendar |
| Bounce rate | Whether your data is clean | Instantly's Academy suggests keeping it under 2% |
| Gmail spam rate | Whether Gmail users report you | Postmaster Tools; Google says keep it below 0.10% |
| Placement test | Inbox, spam or Promotions | Send to your own Gmail, Outlook and Yahoo inboxes |
Postmaster Tools has a catch for small senders. Google's Postmaster Tools help says data might be missing if the total number of messages for a given day is too low. At founder volumes, the test-inbox check is often the only placement signal you get.
For what counts as a decent reply rate, and why vendors count it differently, see our comparison of five cold email reply rate benchmarks. Replies are rarer than opens, so you need more sends before a difference means anything. Our sample-size rule for judging a cold email channel shows how many people to contact first.
When is it worth keeping open tracking on?
Keep it on only when a step in your sequence branches on whether someone opened. Snov.io's article lists the same conditions, except the last row on the right, which is ours:
| Turn open tracking off when | Leave it on only when |
|---|---|
| No step depends on an open | A follow-up branches on "opened" |
| You judge results by replies and calls | You also use a custom tracking domain |
| The mailbox or domain is new or warming up | The mailbox and tracking domain are warmed up |
| Test emails land in spam | Test emails land in the inbox |
Hunter's guide describes another tactic it calls common among cold email experts: track opens while you launch a campaign, then turn tracking off. If you do keep it, Instantly's help page recommends setting up a custom tracking domain before you enable it.
Two rules apply either way. Never write "I saw you opened my last email": with machine opens, it is often untrue and always unsettling. And write each follow-up so it makes sense to someone who never read the first one. Our fix list for cold emails going to spam covers authentication and the other causes to rule out first.
What to change this week
Switch off open and click tracking
Do it in your sending tool's campaign settings, and check for a workspace-wide setting that overrides campaigns.
Send the first email as plain text
No images, no signature logo, at most one link to your own domain.
Set up three test inboxes
One each at Gmail, Outlook and Yahoo. Add them to every campaign and note where each email lands.
Tag every reply
Interested, not now, no, remove me. Count positive replies and calls booked per 100 people contacted.
Once replies are your main number, the work that matters is answering them well. Our guide to turning cold replies into booked meetings covers the next step. If you'd rather not run the sequence by hand, Siela's AI SDR emails only addresses it has verified as deliverable, sends from your own Gmail 2 to 5 minutes apart, and keeps follow-ups in the same thread. Follow-ups stop when the person books, says yes, says no or asks to stop.
Frequently asked questions
Does Gmail penalise emails with tracking pixels?
Google's sender guidelines don't mention tracking pixels. They say Google doesn't track open rates, can't verify open rates reported by third parties, and that low open rates aren't necessarily a sign of spam classification. The warnings about pixels come from sending tools such as Snov.io and Instantly, which say tracking can hurt deliverability, so treat them as vendor guidance.
Does Apple Mail Privacy Protection stop open tracking?
It stops it from being meaningful. Apple says Mail Privacy Protection hides the reader's IP address and prevents senders from seeing whether an email was opened. Litmus, which attributed 76.56% of the opens it tracked in September 2026 to Apple, says opens from these users are not considered reliable. Apple says the feature does not extend to links or attachments.
Is click tracking worse than open tracking for cold email?
Vendors treat it as an added risk. Snov.io says click tracking changes every link into a tracking link and recommends leaving it off unless a sequence step depends on clicks. Hunter's guide quotes one founder advising never to track clicks in cold email. If you need to know who visited, link to a page on your own domain and check your site analytics.
Why did my open rate drop when my emails didn't change?
Often because the mix of email apps on your list changed. Apple Mail with privacy protection can inflate opens, classic Outlook blocks images by default so its readers may not count, and emails in spam register no opens at all. In our made-up example, a list with more corporate Outlook users shows about half the open rate with the same real readership. Check replies and a placement test instead.
Will a custom tracking domain make open tracking safe?
It lowers one risk without removing the pixel. A custom tracking domain stops other users of your sending tool from affecting the reputation of the domain that hosts your pixel. Snov.io says a warmed-up custom tracking domain lowers the risk, but tracked emails can still land in spam more often than emails without tracking.
Sources
- Google: Email sender guidelines (checked 24 Oct 2026)
- Google: Postmaster Tools help (checked 24 Oct 2026)
- Google Workspace Admin Help: Set up an image URL proxy allowlist (checked 24 Oct 2026)
- Apple Support: Use Mail Privacy Protection on iPhone (checked 24 Oct 2026)
- Apple Newsroom: Apple advances its privacy leadership with iOS 15 (7 June 2021)
- Microsoft Support: Block or unblock automatic picture downloads in classic Outlook (checked 24 Oct 2026)
- Litmus: Email client market share (September 2026 data) (checked 24 Oct 2026)
- Mailchimp: About open and click rates (checked 24 Oct 2026)
- Snov.io: How open tracking harms deliverability (9 Oct 2026)
- Instantly Help: Open tracking (checked 24 Oct 2026)
- Instantly Help: Why opens are not being tracked (checked 24 Oct 2026)
- Instantly Academy: Tracking your campaign performance (checked 24 Oct 2026)
- Hunter: Email tracking (Cold Email Guide) (20 Sep 2023)
- Hunter: Use a custom tracking domain (Cold Email Guide) (20 Sep 2023)
- r/coldemail: Is anyone still tracking open rates? (15 Apr 2026)
- r/coldemail: B2B email open rates dropped from 25% to 15% (26 Feb 2026)
- r/coldemail: Stop Tracking Open Rates. Do you agree? (19 Mar 2026)