The BBC today ran a story about so-called ‘spy pixels’ in e-mails, but what exactly are they? Well, e-mails can contain images as well as text. An image can be directly embedded within an e-mail, or the e-mail can contain a link back to the sender’s e-mail server where the image is stored. When you read an e-mail containing such a link, the sender’s e-mail server will see that you’ve accessed the image and know that you’ve read the e-mail they sent.
If you read a spam e-mail containing a link back to the sender’s e-mail server, the spammers will know that your e-mail address is ‘live’ then probably send you a lot more spam. However, a lot of supposedly reputable brands use the same trick. Sometimes they send e-mails that don’t appear to contain any images, but an image doesn’t have to be large. An e-mail can contain a tiny image that consists of just one pixel and will not be noticed against the background.
Thankfully there’s an easy way to stop this spying. If you use a good e-mail program like Mozilla Thunderbird, it can be set up to ignore links in e-mails that refer to remote content. In fact, when you first install Mozilla Thunderbird this is the way it works by default. Many people switch off this protection because they don’t realise what can happen as a result. However, I recommend leaving it switched on, as you can always switch it off for e-mails that you trust.