Microsoft has reduced the number of e-mail messages Hotmail users can send each day to 100 in an effort to prevent spammers from using the service to send spam.
The cap, put in place earlier this month, only applies to users of the company's free Hotmail e-mail service, and not to MSN 8 subscribers or those who pay for MSN Extra Storage, a Microsoft spokeswoman said.
"This change is one way we are preventing spammers from using Hotmail as a vehicle to send the unwanted emails," Lead MSN product manager Lisa Gurry said in a statement.
The move comes amid other efforts by the software company to quash spam, such as tightening its spam filters and taking spammers to court.
Other major e-mail service providers such as Yahoo! and America Online (AOL) have taken a tough stance against spam in recent months, as the problem reaches a critical level.
AOL, for instance, said that it blocked one billion spam messages in one day earlier this month.