Google is extending its hosted e-mail archiving service to hold messages for up to a decade, the company said Wednesday.

Google Message Discovery, which lets users search archived e-mail, debuted in April and supports Microsoft's Exchange and IBM's Lotus Domino e-mail systems. The company priced the service at US$25 per user per year, which includes Google's Postini antispam and antivirus filtering.

Google will now hold e-mail for up to 10 years for $45 per user per year including the e-mail security service. It will still offer Message Discovery at $25 for archiving e-mail for a year or less, according to the company's enterprise blog.

In the U.K, one year or less of archiving will be £12.50 (AUD$32.50) or £22.50 for up to 10 years.

Google claims that companies would spend $200 per user per year for on-premise security and archiving software and hardware.

Businesses are increasingly adopting e-mail archiving software in order to comply with government regulations and legal challenges.

Google's Postini service holds the second-largest market share for hosted security services behind competitor MessageLabs, which Symantec announced Wednesday it plans to buy for US$695 million. MessageLabs holds one third of the market.