Microsoft 365 - change send limits

Hi, @Johnny Broe

From your description, I understand that you are experiencing a sending limit when trying to send an email to about 1000 recipients. This is due to the number of recipient limits, recipient rate limits, message rate limits, and message rate limits set by the email service to prevent spam and resource overconsumption.

First, you need to understand the sending and receiving limits in Exchange Online, which can be found here: Exchange Online limits - Service Descriptions | Microsoft Learn

To modify the limit, you can try the following suggestions:

1. Customise recipient limits. Administrators can customise the recipient limit settings from 1 to 1000, which can be viewed in the following ways: Customizable Recipient Limits in Office 365 | Microsoft Community Hub
2. Send in groups. Classify a large number of recipients into different groups, and each group is counted as one recipient.
3. Increase recipient rate limit. The new ERR will be rolled out gradually, make sure to spread out your email sending over a longer period of time so you can avoid hitting the limit. Reference: Exchange Online to introduce External Recipient Rate Limit | Microsoft Community Hub
4. If you are communicating at large scale internally, consider a high-volume email service. Reference: Manage high volume emails for Microsoft 365 in Exchange Online Public preview | Microsoft Learn

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