how open rate are measured

We know from how open rates are measured that people blocking the display of images in emails, or seeing text-only emails, do not register an open.
  w% {6 o6 R; M5 }' k3 \' A" mWhen your email service sends out your email, they include a piece of code in each one requesting the display of a tiny, transparent (i.e. invisible to the viewer) tracking image.
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When the recipient's browser or email reading software (an email client like Outlook Express) tries to display the email on a screen, it reads that piece of code and sends out a request to the email service for the tracking image.
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The email recipient is unaware of all this, of course. He or she never sees the image, as it's tiny and transparent: the whole process takes place in the background.
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; A8 X7 f$ v0 e( TWhen the service receives the request, it records it and uses it as an indication that the recipient has "opened" the email.

, b4 o& m" Y2 P4 J$ I5 TBy giving each email its own unique tracking image, the service can even tell which email was opened. So not only does it tell you how many emails were "opened," but it also tells you exactly which recipient's emails were opened.

/ S& B% N3 A8 Q" bThis sounds great. If it wasn't for a but or three.

& J% }' X2 S$ M. sFirst, you now see that "opened" actually just means the recipient's software or browser displayed the email such that the tracking image was requested.
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It says nothing about whether the recipient actually read or engaged with your email in any way.

So it is only a rough proxy for what you might call reader interest. (But better than nothing.)
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Second, the tracking image can be activated without the recipient ever actually seeing the email at all.

Many email clients have a preview function, where part of the email is displayed below or to the side of the list of emails in your inbox.

* X5 M' B% \6 F- ^# S3 ?# xSo you can highlight an email on your screen and hit the delete button without ever looking at its content. But the preview function means the email client has tried to display the email and thus registered an "open."

So some of those recorded opens are from recipients who never even looked at your email.
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0 S% z& ?: C; M  I0 aThird, some recipients will read your email and an open is not recorded. Hah! Now we have the reverse case.

How does that happen?
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, v0 {8 Z$ l# h4 w2 y0 N' hYour email service can only track the open if that little tracking image is requested.
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That piece of code is HTML code. So if your recipient gets text-only emails or has an email client that only displays text versions of emails (like many mobile devices), then the image code is ignored and never requested.

No image request means no record of an open. So your recorded email open rate misses out on those people.

And it doesn't end there. Many email clients now refuse by default to display images (see below). So they show the email in its entirety, but ignoring images. Again, the recipient could spend all day reading the email but an open is never recorded as the tracking image was never requested.
4 S, a4 J4 K& EBetter then to extend our definition of inactive to those who never open or click. Even then, if some links in your email (for example in the text version) are not tracked, then you will still get some folk tagged as inactive who aren't. Those who still read your emails, but don't register an open and never follow a tracked link.

; r; s( D6 b( D2 P4 C& vSo don't assume all those tagged as inactive are genuinely disinterested in your emails. Which is why it never does to simply delete inactive email addresses from your list.
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3 U8 I' u2 ^& ?8 D$ P+ t9 a4 `You must give them a chance to (re)confirm their interest through one or more emails deliberately designed to get them to take some measurable action (like signing up again to the list or clicking on a tracked link unique to that recipient.)

英文看起來真累啊

2# lyyxyyl
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習慣就好了

看不大懂 要慢慢看~~~

搞個中文的看的就快了