Microsoft will unveil a major revamping of its Hotmail webmail service next month, with upgrades across the board in security, performance and dealing with spam.

"We listened. We learned. We reinvented Hotmail from the ground up," Microsoft announced ahead of the October 3 events in New York and San Francisco.

"Forget everything you thought you knew about Hotmail. Just don't forget this date."

Hotmail's two main competitors are Google's Gmail and Yahoo Mail. The last time the consumer webmail market got a competitive jolt was in 2004, when Google surprised the world with Gmail and its then-unprecedented amount of email storage.

At that point, innovation in webmail services had stagnated for years but Gmail shook Microsoft, Yahoo and other webmail providers like AOL out of their comfort zone, as they quickly responded by increasing the size of their email inboxes.

Gmail also offered improvements in other areas, most notably with its superior inbox search functionality and with its consolidation of email exchanges into threaded "conversations" in which all replies are grouped within the original message.