Email message rate limit

Message rate limits determine how many messages a user can send from their Exchange Online account within a specified period of time. This limit helps prevent over consumption of system resources by a single sender. If a user submits messages at a rate that exceeds the limit via SMTP client submission, the messages will be rejected and the client will need to retry.

Office 365 sending limits

Limit Per Email   -  500

Limit Per Hour  -  1500 

Limit Per Day  -  10,000

Note:  After the recipient rate limit is reached, messages can’t be sent from the mailbox until the number of recipients that were sent messages in the past 24 hours drops below the limit.

For example, a user sends an email message to 5,000 recipients at 09:00 AM, then sends another message to 2,500 recipients at 10:00 AM, and then sends another message to 2,500 recipients at 11:00 AM, hitting the limit of 10,000 messages. The user won't be able to send messages again until 09:00 AM the next day.

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Article ID: 89802
Mon 10/21/19 10:02 AM
Wed 11/17/21 2:43 PM