How to know when to block images in email

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matthijs
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How to know when to block images in email

Post by matthijs »

In your email client (for ex. Thunderbird) showing of images can be blocked. Advantage is
a) you cannot be tracked (by loading the image from the server the sender knows you opened the email)
b) you're spared to look at ugly images or newsletters

I block showing of images by default. Only sometimes do I allow them to be shown. However, since the senders' email address can be spoofed, how can I be sure were the email came from?

If a spammer would send me a spoofed email newsletter with the from address being a trustworthy one, I might open the mail with images and by that let the spammer know my email address exists.
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VladSun
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Re: How to know when to block images in email

Post by VladSun »

It's more a mail server problem, than a mail client.
Typically, mail servers would check if the reverse DNS record (that is IP to domain name) of the server trying to send mail matches the domain used in the sender.
Also, a SPF records should be (but not reuiqred) defined in the DNS servers serving the sender domain name.
http://www.openspf.org/Introduction
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josh
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Re: How to know when to block images in email

Post by josh »

Which is really a problem in the whole smtp protocool since that mailserver is allowed to be authoritative over itself.

In GMail it has "show images", or "always show images". Usually a quick glance of the text of the email tells me wether it is safe. A spammer won't take the time to write up paragraphs of text that looks like it is from that company, they'll usually just put garbage or stuff related to their keywords
matthijs
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Re: How to know when to block images in email

Post by matthijs »

Exactly. So it's the architecture itself that is unsafe. With a web URL, you can at least check the domain and see who it really belongs to. Unless the root DNS is messed up, of course.
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