Microsoft's free email service MSN Hotmail has passed the 100 million user mark, the software giant announced today.

Hotmail's numbers are Microsoft's own, but it claims it now has 100 million active email accounts. Since Microsoft acquired Hotmail in 1997 it has increased its user base tenfold, says the company.

The Spanish-language version of Hotmail has attracted eight million unique users in March, according to the research firm.

Figures come from a Jupiter Media Metrix study of users in the US, UK, Germany, France, Japan, Australia, Canada, Spain, Brazil, Italy, Argentina and Switzerland.

MSN's instant messaging Messenger Service has also been doing well, reaching 31.9 million unique users worldwide in March. It is the second month in a row that Microsoft, if MSN numbers are true, has beat out AOL's Instant Messenger and ICQ services and the Yahoo Messenger service for the top spot.

The latest figures show a shift in popularity for the erstwhile underdog. In November 2000 MSN Messenger lagged behind AOL Instant Messenger in terms of US users (21.5 million to 10.3 million), according to Jupiter.