Sending, receiving, and organizing email in Outlook.com
Hi! To help protect against abuse by spammers, Outlook.com limits the number of email messages that you can send in a single day, as well as the number of recipients for a single message.
If you recently created a new Outlook.com account, or your emails are often mark as spam, a low sending quota is a temporary restriction which is upgraded to the maximum limit as soon as you establish credibility in the system.