You should be careful from such mails as they as sent by scammers in order to steal our coins. Most of us fall into such traps because we don't really look at the URL of the site and download software from those unknown websites basically they are phishing sites. Another user has reported such type of scam a few months ago where he also shared the scam information with the community.

Here's the link of the thread where Nwada001 shared information about a similar MetaMask scam: Scam targeting Metamask wallet user's

These scammers often use fake URL's in order to steal coins of the user's. The official URL of MetaMask is https://metamask.io/ and if the site which you visited has a different URL than that's 100% a phishing site set by scammers. It's always needed to check the URL of the page before entering any sensitive information and unfortunately most of us don't really give much importance to URL and just see in inner contents of a site and that's why those malicious people get success with their negative activites.