How a read email ends up marked unopened

If a recipient replied to an email your tracker still marks as unopened, believe the reply. The person read your message; their mail app simply never loaded the tracking image, so no open was recorded. Mailtrack's help center calls this out in an article titled My email has been replied to but Mailtrack still says it hasn't been opened, and Streak and NetHunt give the same explanation in their own support pages. The useful part is what it tells you about every other email marked unopened.

An open is an image request and nothing more

Open tracking works by adding a tiny image to the email. Mailtrack describes its own as a 0x0 .png file. When the reader's mail app fetches that image from the tracker's server, the tracker records an open. If the image is never fetched, there is nothing to record. Streak's support page on replies with no tracking information says it directly: if the pixel is never accessed, Streak receives no information, so a tracked email can be read without registering a view.

So "unopened" has two possible meanings. Either nobody has looked at the email, or somebody read it in an app that held the image back. The tracker cannot tell those apart, because in both cases it heard nothing.

Where the image gets held back

• Classic Outlook on a work computer. Microsoft's support page on automatic picture downloads says Outlook is configured by default to block them, and lists avoiding tracking pixels as one of the reasons. Pictures load only when the reader clicks Download Pictures, changes the setting, or adds you to their Safe Senders list.
• Gmail with images switched off. Gmail shows images automatically by default, but its help page on turning images on or off offers an Ask before displaying external images setting, and says Gmail also holds images back when it thinks a sender or message is suspicious.
• Other apps and filters. Streak notes that some mail clients have built-in protections that stop tracking from working as you would expect.
• Your own side. NetHunt's article on replies to unopened emails puts tracking not being enabled first on its list. Check that the message actually went out tracked before blaming the reader.

Measure how much your tracker misses

You do not have to guess how common this is on your own list. Your replies already contain the answer. Take everyone who replied to a campaign or sequence and count how many of them have zero recorded opens. Those people certainly read the email, so the share of repliers with no open is a rough measure of how often your tracker misses a real reader.

Here is how that works with illustrative numbers. Say 40 people replied and 6 of them show no open. That is 15 percent of known readers the pixel never saw. If the same campaign recorded 120 opens, the real number of readers is closer to 141, because 120 is what remains after missing about 15 percent. Treat this as a floor rather than a precise figure. People who reply are not a perfect sample of everyone who reads, and a list full of corporate Outlook users will miss more than a list of Gmail addresses.

A reply proves the email was read. An unopened status only proves the image did not load.

What to do with an unopened email

• Write the follow-up as if the first email was read. Never open with "did you see my last email?" when the honest answer may be yes.
• Count a click or a reply as stronger than any open. Both need the reader to act, and neither depends on images loading.
• Expect more blind spots on business lists. If your prospects work at companies running Outlook, judge them on replies and clicks, and expect fewer opens.
• Check your own setup first when a whole batch shows nothing. One email with no opens is normal; twenty usually means tracking was off.

How Fast Mail Tracker records a reply with no open

In Fast Mail Tracker, each recipient's status is the strongest thing we have actually seen from them: sent, opened, clicked or replied. A reply moves that person to Replied even if their open count is still zero, so a read email never stays labelled as unread once they answer. A reply is recorded when the extension sees a message from someone other than you in the Gmail thread. We do not invent an open to fill the gap, though. The open count shows only opens we recorded, and a campaign's open rate counts only people with a recorded open, so the open, click and reply rates sit side by side and the difference between them is there for you to read. That gives you the repliers with no open that the calculation above needs.

Fast Mail Tracker is in early access while Google's security review completes, so places are limited; to see replies, clicks and opens for each recipient on your own emails, use the install button below.