Email tracking pixels are tiny, often invisible images embedded in emails, primarily used to collect data on recipient engagement. They are commonly employed to determine if an email has been opened, when it was opened, and sometimes even the recipient's general location.
This data is invaluable for marketers, enabling them to gauge campaign performance and optimize future sends. Without such tracking, understanding the reach and initial impact of email campaigns would be significantly more challenging.
However, a common concern among senders is whether these pixels negatively affect email deliverability, potentially pushing messages into spam folders instead of the inbox. This is a complex issue, as mailbox providers constantly evolve their spam filtering techniques. While tracking pixels themselves aren't inherently problematic, certain implementations or contexts can indeed pose risks to your deliverability.
What is an email tracking pixel?
An email tracking pixel is typically a 1x1 transparent GIF image embedded in an HTML email. When the recipient opens the email and their email client loads images, a request is sent to the server hosting this tiny image. This request is recorded, indicating that the email has been opened.
This mechanism allows email service providers (ESPs) and marketing platforms to gather data such as open rates, the time of open, and sometimes the IP address of the opener, which can infer general geographic location. It's a non-intrusive way to measure engagement that has been a cornerstone of email analytics for years, as explained by email deliverability experts.
However, recent privacy changes, such as Apple's Mail Privacy Protection, have altered how open tracking works for many users, as these features automatically load all remote content, including tracking pixels, before a user even views the email. This has led to inflated open rates and a need for marketers to re-evaluate how they measure engagement.
Tracking pixels and sender reputation
The primary way tracking pixels can affect deliverability is tied to the domain from which the pixel is loaded. If your tracking pixel points to a domain with a poor reputation, or one that is shared across many senders with varying practices, it can raise red flags with spam filters.
Mailbox providers (MBPs) often analyze all domains present within an email, including those used for tracking. If the domain hosting your tracking pixel is associated with spamming activities, or if it appears on a public blocklist (or blacklist), your emails may be filtered to the spam folder or even rejected.
Shared tracking domain
Often used by default by some email sending platforms, especially cold email tools. The tracking pixel is hosted on a domain shared by many users. This can lead to your emails being flagged as spam due to the negative actions of other senders using the same domain, even if your practices are legitimate. Spam filters are more likely to be suspicious of shared, generic domains.
Custom tracking domain
A custom tracking domain (sometimes called a branded tracking domain) uses a subdomain of your primary sending domain, like track.yourdomain.com. This allows you to build a dedicated reputation for your tracking links and pixels, separating it from the shared reputation of your ESP's default domain. It signals to MBPs that the tracking is aligned with your brand, generally improving trust and deliverability.
Mitigating tracking pixel risks
To minimize the risk of tracking pixels affecting your email deliverability, you should adopt several best practices. The most critical step is to ensure your tracking domains are properly configured and managed.
Always use a custom tracking domain that aligns with your sending domain. This means that instead of a pixel loading from espprovider.com/track.gif, it should load from track.yourdomain.com/track.gif. This establishes a direct reputation link between your primary domain and your tracking activities. This also ties into how your subdomain alignment affects deliverability.
Prioritize security
Ensure all your tracking pixels and links utilize HTTPS. Many email clients and internet service providers now actively flag or block non-secure (HTTP) content, which can severely impact your email's journey to the inbox. This also helps build a trustworthy sender reputation. If you're using non-HTTPS engagement tracking, you may face deliverability issues.
Here's an example of a CNAME record for a custom tracking domain that you would typically set up in your DNS records.
Example CNAME record for a custom tracking domainDNS
With increased focus on user privacy, the effectiveness and implementation of tracking pixels are continually evolving. Privacy features from major mailbox providers, like Apple's Mail Privacy Protection, are designed to protect user data by pre-loading images, which includes tracking pixels.
This doesn't mean tracking pixels are dead, but it does mean the data they provide, particularly open rates, may no longer be entirely accurate or reliable for all recipients. Mailbox providers are also getting smarter about detecting suspicious tracking practices, especially in cold outreach or unsolicited emails. They might directly mark emails as spam if tracking pixels are deemed to be part of a malicious or unwanted campaign.
Ultimately, the presence of a tracking pixel is just one of many factors that influence email deliverability. A strong sender reputation, built on consistent sending volume, low complaint rates, and high engagement, remains the most crucial determinant for inbox placement. Always focus on providing value to your recipients and maintain technical solutions for email deliverability.
Views from the trenches
Best practices
Monitor your custom tracking domain's reputation as closely as you monitor your main sending domain. If it gets blocklisted, it will affect your deliverability.
Implement a slow rollout of tracking pixels when enabling them for the first time, allowing you to observe any impact on your deliverability before a full deployment.
Always use TLS/SSL for tracking pixels, especially when emailing recipients in regions with strict data privacy regulations like the EU, where explicit permission for tracking may be required under GDPR.
Common pitfalls
Relying on generic or shared tracking URLs provided by your ESP without setting up a custom, branded CNAME record, which can tie your email reputation to other senders using the same shared infrastructure.
Ignoring the security of your tracking pixels by using HTTP instead of HTTPS, which can trigger spam filters and security warnings for recipients.
Neglecting to monitor your deliverability metrics when introducing tracking pixels, missing potential negative impacts on inbox placement.
Expert tips
Regularly check your tracking domains against common blocklists (or blacklists) to ensure they are not negatively impacting your sender reputation.
Consider alternative engagement metrics beyond open rates, such as click-through rates and conversion rates, especially with the rise of privacy features that impact pixel accuracy.
Ensure your email authentication (SPF, DKIM, DMARC) is perfectly configured, as a strong authentication foundation can help mitigate minor issues related to tracking pixels.
Expert view
Expert from Email Geeks says they only see tracking pixels dropping deliverability when the CNAME branding is messed up.
2019-10-08 - Email Geeks
Expert view
Expert from Email Geeks says a shared URL across multiple senders can carry a shared reputation, and proper branding and configuration are required for tracking pixels.
Apple's Mail Privacy Protection, are designed to protect user data by pre-loading images, which includes tracking pixels.
