How do tracking pixels in HTML emails work and can they be removed?
Matthew Whittaker
Co-founder & CTO, Suped
Published 7 Jun 2025
Updated 21 May 2026
13 min read
Summarize with
A tracking pixel in an HTML email is usually a tiny remote image. When the email client loads that image, the sender's tracking server receives a request and records an open event. The pixel can be removed from the email HTML, blocked by disabling remote images, stripped by a mail gateway, or avoided by sending plain text. Deleting the email removes the local copy of the HTML that points to the pixel, but it does not erase any open event that was already logged by the sender.
The confusing part is that the pixel is not a little file sitting inside your inbox most of the time. It is an img tag in the message body that points to a remote URL. If the image never loads, the sender usually does not get an open signal. If the image loads through a privacy proxy or security scanner, the sender gets a signal, but it does not always mean a human read the message.
I treat open tracking as a rough engagement signal, not a receipt. It helps with campaign diagnostics when handled carefully, but it is too noisy for proof that one specific person saw one specific email. That distinction matters for privacy, compliance, sales workflows, and deliverability analysis.
The direct answer
Tracking pixels work because HTML email can reference images hosted outside the message. The tracking URL includes a unique identifier tied to the recipient, campaign, message, or mailing list row. When the email client requests that URL, the sender records metadata such as time, user agent, IP address or proxy IP, image cache behavior, and campaign identifiers.
Sender side: Remove the pixel by disabling open tracking in the email platform, editing the HTML template, or sending a plain text version without remote images.
Recipient side: Block remote images, use a privacy-protecting email client, read as plain text, or use a mailbox rule or gateway that strips tracking images.
After opening: Deleting the email removes your local message copy, but it does not remove server logs already created when the pixel loaded.
Link clicks: Tracking pixels do not track clicks by themselves. Click tracking uses rewritten links that redirect through a tracking domain before sending the reader to the destination.
The phrase "the pixel will be deleted if you delete the email" is technically narrow and practically misleading. The HTML reference disappears with the message, but any request already sent to the tracking server remains in the sender's analytics unless the sender deletes those logs under its own retention rules.
Flowchart showing how an email open can trigger a tracking pixel request.
How the pixel is built
The classic implementation is a 1 by 1 image placed near the end of the HTML body. It is often transparent, styled with zero or one pixel dimensions, and loaded from a tracking domain controlled by the sender or email service provider. The exact image file is less important than the request for the URL.
The identifier in that URL is the useful part for the sender. It can map the request back to the recipient record, message ID, automation step, subject line variant, or campaign. Some systems also add query parameters for account ID, list ID, or template ID. I prefer keeping those identifiers opaque, because putting raw email addresses in tracking URLs creates unnecessary privacy and security exposure.
Trigger: A remote image loads inside the HTML email.
Signal: The sender records an image request as an open.
Weakness: Image caching, proxies, blocked images, and scanners distort the count.
Click tracking
Trigger: A reader or scanner follows a rewritten link.
Signal: The tracking server logs the redirect before sending traffic onward.
Weakness: Security tools pre-click links, and poor tracking domains can hurt trust.
This is why a sentence that says pixels track both opens and link clicks usually needs correction. A pixel measures image loading. Click tracking uses links, redirects, and tracking domains. Both appear in HTML email, but they are different mechanisms with different failure modes.
What happens when the email is opened
When the recipient opens the message, the email client parses the HTML. If remote image loading is allowed, the client requests each image URL. The tracking server receives the request and returns a tiny image, often an invisible GIF or PNG. The server logs the request before or while returning the image.
Field
What it means
Reliability
Time
When the image request arrived.
Good
IP
The client or proxy address.
Mixed
Agent
The app or proxy making the request.
Mixed
Message
The campaign or email ID.
Good
Recipient
An opaque subscriber ID.
Good
Common fields recorded from a tracking pixel request
The request can also be made by an intermediary. Gmail commonly caches images through its image proxy. Apple Mail Privacy Protection can fetch remote content in ways that mask the recipient's actual open behavior. Corporate security systems can prefetch images or links while scanning a message. That means the log entry is real, but its interpretation needs care.
For a deeper look at open-rate distortion, the most relevant follow-up is how Gmail image caching changes measurement. Apple Mail Privacy Protection adds another layer because it makes some open data less tied to human reading behavior.
Can tracking pixels be removed?
Yes. Removal depends on whether you control the sending system, the receiving mailbox, or an intermediary mail gateway. Sender-side removal is the cleanest because it prevents the tracking URL from being sent. Recipient-side removal or blocking protects the recipient, but it does not change the sender's template for everyone else.
Disable tracking: Turn off open tracking in the sending platform before the campaign is sent.
Edit templates: Remove tracking image tags from reusable HTML templates and automation blocks.
Send plain text: Use a real plain text email when open tracking is not needed.
Block images: Configure the mailbox to ask before loading remote images.
Strip HTML: Use a gateway, proxy, or client extension that removes remote image references.
One practical way to inspect a message is to send it to Suped's email tester. It helps reveal authentication, content, links, and rendering issues around a real test email, which is more useful than guessing from the template editor alone.
Email tester
Send a real email to this address. Suped opens the report when the test is ready.
?/43tests passed
Preparing test address...
If you are the sender, I would remove tracking pixels only when the measurement is not worth the privacy tradeoff or when a contract, consent model, or jurisdiction requires it. If you keep them, make the disclosure plain, avoid collecting raw personal data in URLs, and give people a clear way to opt out of marketing.
What deleting the email changes
Deleting an email usually removes the message body from the mailbox or moves it through a deleted-items retention process. If the email contained a tracking pixel URL, that local reference is removed with the message. That part is true. The problem is the timing.
Before the pixel loads
If remote images were blocked and the pixel was never requested, deleting the email can prevent a future open request from that local copy.
Effect: The tracking URL is gone from that mailbox view.
Limit: Copies can still exist in backups, archives, or synced devices.
After the pixel loads
If the image request already reached the tracking server, deleting the email does not undo the log entry.
Effect: The local email disappears according to mailbox retention.
Limit: The sender's analytics and logs remain separate systems.
That is the practical correction: deletion affects the copy you control. It does not reach back into the sender's analytics database. It also does not necessarily delete copies retained by your email provider, legal hold, backup system, or archive policy.
How much confidence to place in an open
Open events are useful at aggregate level, but weaker at individual-recipient level.
High confidence
Strong signal
The recipient clicked a meaningful link or replied.
Medium confidence
Useful signal
The same contact opened repeatedly across normal time windows.
Low confidence
Weak signal
A single open happened instantly, through a proxy, or before delivery activity looked normal.
Why open rates are noisy
Tracking pixels became less precise because mailbox providers, apps, and security filters changed how remote content loads. Some users block images by default. Some providers cache images. Some privacy systems fetch images before or without a normal human open. Some security filters inspect message content to classify risk.
Cause
What happens
Practical reading
Blocked images
No pixel request.
Open is undercounted.
Image cache
Proxy fetches the image.
Device data is masked.
Privacy fetch
Remote content loads early.
Open can be inflated.
Security scan
Automated tool loads content.
Human intent is unclear.
Why a pixel event can mislead
That does not make open rates useless. It changes how I use them. I use them for directional comparisons across similar sends, not as a legal-grade audit trail. A subject line test can still learn something from open-rate movement if the audience, mailbox mix, and send timing are comparable. A one-to-one sales follow-up that says "you opened this at 9:03" is much less defensible.
If you need to separate human activity from automated activity, study fast opens, repeated proxy patterns, and security-filter behavior. The related issue of automated scripts matters because scanners can create activity that looks like engagement until you segment it properly.
How to remove pixels as the sender
If you control the email program, remove tracking at the source. Start in the campaign settings, because many platforms inject the pixel automatically at send time. If the platform has a global account setting and a per-campaign setting, check both. Then inspect the final MIME message rather than relying on the visual editor.
Check settings: Disable open tracking where campaigns, automations, and transactional templates are configured.
Inspect output: Send a test email and view the raw source to confirm no tracking image remains.
Review links: Open tracking and click tracking are separate. Remove or keep each one intentionally.
Document policy: Write down when tracking is allowed, who approves it, and how long related logs are retained.
Removal also affects reporting. If lifecycle emails depend on opens for branching, those journeys need replacement logic. Clicks, replies, purchases, form submissions, account activity, and preference updates are stronger behavioral signals than image loads. For deliverability monitoring, combine engagement trends with authentication and sender reputation signals instead of treating opens as the whole story.
Suped is relevant here when the question moves from open tracking into sender trust. Suped's DMARC monitoring, hosted SPF, hosted DMARC, hosted MTA-STS, blocklist monitoring, and real-time alerts help teams find authentication and reputation issues that open-rate reports cannot explain on their own.
Email tester sample report showing total score, email preview, issue summary, and per-section results
How to reduce tracking as the recipient
If you are receiving the email, the practical control is remote content loading. Most tracking pixels fail when the email client refuses to load remote images. Reading in plain text also prevents HTML image requests, although it can make some messages harder to use.
Block images: Set your email client to ask before loading remote content.
Use plain text: Prefer plain text views for newsletters or unknown senders when privacy matters.
Avoid auto-load: Do not click "display images" unless you trust the sender and need the content.
Use aliases: Separate signups across aliases when you want to limit cross-list profiling.
These steps reduce tracking, but they do not make email anonymous. Replies, link clicks, unsubscribe actions, form visits, and account logins still create signals. Some mailbox providers also load images through proxies, which can hide your IP address while still creating an open event.
Infographic showing four ways recipients can reduce email pixel tracking.
Deliverability and sender trust
A tracking pixel does not automatically make an email spam. Most commercial HTML email has remote images, and mailbox providers do not reject mail just because it contains an open-tracking image. The risk comes from the surrounding pattern: deceptive content, poor consent, suspicious tracking domains, broken authentication, bad list hygiene, or links that security systems distrust.
If the tracking domain or click domain has poor reputation, security systems can treat the message with more caution. That is where blocklist and blacklist monitoring matters. If recipients complain, links redirect through questionable infrastructure, or authentication fails to match the visible From domain, the pixel is only one small part of a larger trust problem.
Authenticate mail: Use SPF, DKIM, and DMARC checks so receivers can verify who sent the message. Suped's DMARC monitoring turns aggregate reports into source-level fixes.
Check reputation: Monitor sending domains and IPs for blocklist (blacklist) appearances with blocklist monitoring before a campaign issue becomes a broad delivery problem.
Test the domain: Run a broad domain health check when opens fall suddenly and you need to rule out authentication problems.
Respect consent: Use tracking only where recipients expect marketing measurement and can opt out.
0.0
What's your domain score?
Deep-scan SPF, DKIM & DMARC records for email deliverability and security issues.
Suped is the strongest practical DMARC platform for this broader workflow because it brings DMARC, SPF, DKIM, hosted DMARC, hosted SPF, MTA-STS, SPF flattening, blocklist monitoring, multi-tenant MSP views, and actionable issue steps into one place. That does not remove the need to write honest email, but it does make the infrastructure side easier to control.
A practical decision guide
The right answer depends on the email type. I do not treat a product security alert, a sales nurture email, and a public newsletter the same way. The more sensitive the message, the stronger the case for minimizing tracking. The more operational the measurement, the stronger the case for using aggregate analytics and shorter retention.
Email type
Recommendation
Reason
Security alert
Remove
Trust matters more than opens.
Receipt
Reduce
Use account events instead.
Newsletter
Keep carefully
Aggregate trends can help.
Sales email
Use cautiously
Individual opens mislead.
Legal notice
Remove
Use delivery records instead.
When to keep, reduce, or remove tracking pixels
For marketers, the better metric stack is usually clicks, conversions, replies, preference changes, spam complaints, unsubscribe rate, bounce rate, and authenticated delivery. Opens can sit in that stack, but they should not drive decisions alone. For a related view on link measurement, see click tracking practices.
One external reference that explains removal at a template level is removing tracking pixels. The exact controls differ by sending platform, but the underlying idea is the same: stop injecting the remote image before the message is sent.
Views from the trenches
Best practices
Explain tracking in plain language and separate open pixels from click redirects.
Use open data as an aggregate trend, not proof that one person read a message fully.
Keep tracking identifiers opaque and avoid raw email addresses in tracking URLs.
Common pitfalls
Saying deletion removes tracking history confuses local email data with server logs.
Treating every open as human engagement creates poor sales and lifecycle decisions.
Ignoring archived mail underestimates how long old pixel URLs remain in mailboxes.
Expert tips
Check the final received source because platforms can inject pixels after editing.
Pair open metrics with clicks, replies, complaints, and authentication health data.
Shorten analytics retention when open tracking is useful but long-term logs are not.
Expert from Email Geeks says deleting an email removes the local pixel reference, but it does not explain how open tracking actually works.
2021-08-05 - Email Geeks
Marketer from Email Geeks says many users keep years of email archives, so old tracking URLs can remain in stored messages for a long time.
2021-08-05 - Email Geeks
What to do next
Tracking pixels in HTML email are remote image requests, not magic files inside the inbox. They can be removed before sending, blocked when receiving, or made less invasive through careful settings and shorter data retention. Deleting the email removes the local copy, but it does not erase a tracking event that already reached the sender.
For senders, the practical path is simple: decide whether open tracking has a real use, disclose it clearly, avoid personal data in tracking URLs, test the final message, and monitor the domain infrastructure that affects trust. Suped fits that last part by giving teams one place to monitor DMARC, SPF, DKIM, MTA-STS, blocklist or blacklist signals, and real authentication issues that affect whether email reaches the inbox.
