The number of inbound emails that can be queued after the daily email limit is reached are now equal to the daily email rate limit. After this limit is reached, any inbound emails will bounce. Email services should be reviewed and Requeue Message failure response option should be used only for high-priority services
Where: This change applies to Lightning Experience and Salesforce Classic in Enterprise, Professional, Unlimited, and Developer editions
Why: For example, if you have 10 Salesforce licenses, you can receive 10,000 inbound emails before you reach your daily limit. When you reach that limit, additional inbound emails are queued for processing if the failure response option on the email service is Requeue Message. After 10,000 emails are queued, all additional inbound emails for that day bounce
