Since 9 February, users of Google's Gmail service might have been left concerned by an alarming new icon on their emails.
A red, broken padlock has appeared in the corner of some messages - the kind of visual queue that's usually associated with insecure browsing and other sinister internet happenings.
The icon is Google's way of letting you know that you have received a message from someone (or are about to send a message to someone) whose email server doesn't support "Transport Layer Security" (TLS) - an encryption process added to all inbound and outbound emails, ensuring that only the person whom the message was sent to will be able to open it.
The new Gmail padlock indicates you've received a message from someone whose email provider isn't using TLS.
This doesn't mean it's filled with malicious bugs or is set to pinch your passwords, but rather that you should be "extra careful about replying to, or clicking on links in messages that you’re not sure about".
So, don't go deleting every message with a red padlock - just be aware that you might not want to send them sensitive information (bank account details, personal address, Netflix password). Stay safe.