I am unable to send emails

The error message you are receiving indicates that your tenant has exceeded its daily limit for sending emails to external recipients from your onmicrosoft.com domain. This limit is set by Microsoft to prevent the distribution of unsolicited bulk messages and is capped at 100 external recipients within a 24-hour rolling window for onmicrosoft.com domains.

To resolve this issue, you can consider the following options:

1. Wait for the limit to reset: The limit is tracked over a 24-hour rolling window, so you can wait until the count for the most recent 24-hour period falls below the limit.
2. Use a custom domain: If you need to send emails to more external recipients, consider purchasing and migrating to a custom domain. This will allow you to send emails without being subject to the onmicrosoft.com domain limitations.
3. Use Azure Communication Services: For bulk or high-volume emailing to external recipients, you may also consider using Azure Communication Services email.

If you continue to experience issues, you may want to check your tenant's email sending limits and ensure that you are not exceeding them in the future.