Email is not sent from Dynamics 365 and the following alert is found within the mailbox record:

"An unknown error occurred while sending the email message [Email Subject] through the mailbox [Mailbox Name]. The owner of the associated email server profile Microsoft Exchange Online has been notified. The system will try to send the message again later.

Email Server Error Code: Exchange server returned UnknownOutgoingEmailIntegrationError ErrorSubmissionQuotaExceeded exception."


This error is logged if the mailbox has exceeded Exchange Online quota limits. Example: Ten thousand emails within 24 hours. For details on Exchange Online sending limits, refer to the following article:


Avoid exceeding the Exchange Online quota limits or use another email service that specializes in sending bulk email (example: Dynamics 365 for Marketing). The following is an excerpt from the Exchange Online sending limit documentation:

"Exchange Online customers who need to send legitimate bulk commercial email (for example, customer newsletters) should use third-party providers that specialize in these services."

Need more help?

Expand your skills
Explore Training
Get new features first
Join Microsoft Insiders

Was this information helpful?

What affected your experience?

Thank you for your feedback!