Who’s leaking my personal details?

QI’m hot on security, so I was annoyed to receive an email containing personal details, right down to my postcode. My question is how did these scam artists get my details? Are browser plug-ins capable of stealing personal details? I use Ghostery, HTTPS Everywhere and ublock Origin. Is there any way to know if certain companies are selling my details? Jon Winchester

AThere’s no straightforward answer, and any one of your theories could be right. One clue, though, might be found in the formatting of your postcode in the phishing email that you forwarded to us. We noticed that the letters are in lower case, and it lacks a space between the two halves. Do you recall typing it this way recently into any online forms, perhaps when using a phone or tablet? If so, the company behind it is in some way responsible for your email.

Another way to track sources of leaks is to use a unique email address for each of the services you use. With Gmail, you can create these by adding a plus (‘+’) after the first part of your address: Yourname+nameofonlineservice@ gmail.com, for example (see screenshot). As spammers aren’t interested in manually checking individual email addresses, they’ll use this when they fire junk mail at you — and then you’ll have a good idea who’s leaking your details.