Google’s Gmail will require bulk senders to begin authenticating their emails in February 2024 to stay under a reported spam threshold, the company said on Tuesday.

The new rule will address users sending more than 5,000 messages to Gmail accounts in one day.

Gmail’s AI-powered defenses already stop more than 99.9% of spam, phishing and malware from reaching inboxes and block nearly 15 billion unwanted emails every day, the company said. "But now, nearly 20 years after Gmail launched, the threats we face are more complex and pressing than ever."

According to Google, many bulk senders don’t appropriately secure and configure their systems, which allows cyber crooks to easily attack or hide.

While Google said its 2022 requirement to have some form of authentication cut unknown messages by 75%, decluttered inboxes and blocked billions of bulk malicious messages with higher precision, the new format next year will require a series of additional failsafes including stronger authentication standards, a one-click step to unsubscribe and a spam rate threshold for senders.

Yahoo will also work with Google to tackle malicious spam sneaking into inboxes via bulk messages.

"No matter who their email provider is, all users deserve the safest, most secure experience possible," said Marcel Becker, Yahoo’s senior director of product. "In the interconnected world of email, that takes all of us working together. Yahoo looks forward to working with Google and the rest of the email community to make these common sense, high-impact changes the new industry standard."

Google has provided a set of guidelines for bulk senders ahead of the February 2024 deadline.