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Open tracking
Understand how this feature works, its limitations, and whether it's right for your needs.
We don't recommend this feature for most use cases
Open rates can be unreliable and may affect your inbox placement.
How it works
When this feature is enabled, Sendfully inserts a tiny invisible image at the end of each HTML email. When a recipient's email client loads that image, we register that the email was opened.
Why the data is often unreliable
Email clients behave differently, which creates two problems: opens that never get counted, and opens that get counted when no one actually read the email.
Many email clients don't load images automatically. Recipients might read your entire email without ever loading external images, so no open gets recorded. Corporate security systems sometimes remove images entirely.
Some email systems load images preemptively. Security scanners and privacy features may fetch all images before the email reaches the recipient's inbox, registering an open before anyone has seen it.
This only works with HTML emails. Plain text messages don't support embedded images, so opens can't be recorded for them.
Given these factors, open rates provide an incomplete picture of how recipients interact with your emails.
Effect on deliverability
This feature shouldn't prevent your emails from being delivered, but it can influence where they end up. Email providers sometimes treat messages with embedded pixels as promotional content, which may affect inbox placement.
For transactional emails like password resets or receipts, we suggest leaving this feature off.
Better ways to measure engagement
If open rates are unreliable, what should you measure instead?
Link clicks. When someone clicks a link in your email, you know they engaged with it. This is concrete evidence of interest, not just that an image loaded.
Downstream actions. Your emails likely have a purpose beyond being read - a call-to-action like visiting a page, signing up, or making a purchase. Measuring those outcomes tells you whether your emails are actually working.
Situations where this feature helps
Even with its limitations, open rates have some valid uses:
- Spotting trends over time - Absolute numbers may be off, but patterns across many sends can still surface useful insights
- Comparing subject lines - A/B tests remain valid since both variants face the same measurement issues
- Finding inactive subscribers - Persistently low engagement signals can help identify contacts to remove from your list
Enabling this feature
If you still want to use it after considering the tradeoffs:
- Go to Settings > Analytics
- Turn on Open tracking
TIP
You'll need a verified sending domain before you can enable this.