The email throttling feature allows noninteractive email providers to adhere to a per-minute email sending limit, which prevents errors that are currently triggered when the system attempts to send more emails than the provider can handle. When email throttling is enabled, sending limits for Microsoft 365 email providers will be set automatically; manual configuration is required for all other email providers.
Reference:
https://docs.microsoft.com/en-us/dynamics365-release-plan/2020wave2/finance-operations/finance-operations-cr