Mimecast shareholders will receive $80 in cash for each share held, which equates to a premium of 6.7% to Monday's close. Shares of the company rose about the same to $79.75 in premarket trading on Tuesday, nearly matching the offer price.

Founded in 2003, Mimecast provides a range of email security products, such as systems to block malicious web links, phishing attempts and attackers using fake identities in order to trick their victims into revealing sensitive information.

The company, however, fell victim to hackers in January when they hijacked its products in order to spy on its customers, which had compromised the certificate used to guard connections between its products and Microsoft's cloud services.

The deal, expected to close in the first half of 2022, has a "go-shop" period of 30 days for Mimecast to court other offers.

(Reporting by Chavi Mehta in Bengaluru; Editing by Shinjini Ganguli)