In response to feedback from Office 365 customers, the recipient rate limit for Office 365 P1 plan has been increased to allow users to send email to up to 1,500 recipients per day. Previously, the recipient rate limit for users of Plan P1 had been set at a maximum of 500 recipients per day.

Recipient rate limits exist to discourage users from sending large volumes of unsolicited commercial email, commonly referred to as spam. These limits protect the online service from becoming a source of spam and, as a result of these protections, keep O365 customers’ email messages flowing. Datacenter enhancements have allowed us to increase this limit while maintaining the same level of protection.

These limits apply both to email messages sent within an organization and those delivered to external organizations. The best way to avoid exceeding the recipient rate limit is to use distribution groups when sending messages to large numbers of recipients. Distribution groups stored in the shared address book are counted as a single recipient toward the recipient rate limit. For more information, see Strategies to Support Bulk Email. Exchange Online customers who need to send legitimate bulk commercial email — such as customer newsletters – should continue to use third-party providers that specialize in these services.