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7

Almost all e-mail clients, including webmail clients, block external images by default since several years ago, to a large part exactly to prevent using this technique of determining if a mail has been opened.

nielsm
– nielsm

2010-01-07 18:45:34 +00:00
Commented Jan 7, 2010 at 18:45
Please dont do this for public facing services. This is almost 100% considered "questionable" activity in email. Many applications will block this behaviour directly, and many scanning applications will look for images that cannot be seen by the user (0,0 size, 100% transparent, etc)

GrayWizardx
– GrayWizardx

2010-01-07 18:51:46 +00:00
Commented Jan 7, 2010 at 18:51
1

I agree with GrayWizard, it's better to include a real image in the email, like a logo, and send the unique ID inside the url like <img src="blah.com/logo.php?id=1234"> and that url spits out the mime header & binary data for an actual image, not a HTML page.

TravisO
– TravisO

2010-01-07 19:25:52 +00:00
Commented Jan 7, 2010 at 19:25

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create code fences with backticks ` or tildes ~
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like so
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```python
def function(foo):
print(foo)
```
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