A total of 711 million email addresses, some with related passwords, have leaked onto the internet after a security researcher discovered the workings of a misconfigured spambot.
The finding was made by security researcher 'Benkow', who claims to have discovered the Netherlands-based 'Onliner' spambot server containing not just email addresses, but also passwords and details about email servers.
The purpose of a spambot is to send out millions of emails at a time, but without them being trapped by the spam filters in place on all major email systems.
By using the details stored on the server, the botnet could circumvent many of these filters, by making the messages appear as if they had been sent legitimately.
The spammers apparently failed to secure one of their servers, meaning that Benkow was able to download the entire contact database.
Troy Hunt, who runs the security alert site HaveIBeenPwned, described the breach as the largest he's ever loaded into his security database, and that it's "almost one address for every single man, woman and child in all of Europe".
How, exactly, such a large database of contact details was put together hasn't been explained, but Hunt suggests that many of the details are an amalgamation of other large hacks in the past few years, such as the LinkedIn data breach.
While the aim of this particular spammer was ostensibly to send more spam (and thus, malware that could do even more damage), it'd still be a good idea to change your passwords and enable two-factor authentication - whether or not your embarrassing 20-year-old Yahoo Mail address was caught up in the breach.
Dr Kuan Hon criticises GDPR consent emails that will only eviscerate marketing databases and 'media misinformation'
Apple squashes Steam Link app on 'business conflicts' grounds
Philip Hammond wants to forget rules that the UK agreed with the EU to ban non-European companies from the satellites
Instapaper to 'go dark' in Europe until it can work out GDPR compliance