Error Data Size Limit Exceeded during email submission

Products

• Email Security.cloud
• Email Threat Detection and Response

Issue/Introduction

One or more users are unable to submit false negative emails using the Outlook email submission add-in.

ErrorDataSizeLimitExceeded

Environment

• Email Security.cloud
• Outlook Email Submission add-in
• Exchange 2016
   

Cause

The Outlook submission add-in sends a request to Exchange Web Services (EWS) to get the base64 encoded email content. However, if the EWS response is greater than 1 Megabyte, the email content would not be retrieved due to the size limitation.

The size limit applies to Exchange 2013 and 2016 on-prem solutions. There is no limit when submitting on a hybrid environment with Office 365, standalone Office 365 or Exchange Online.

For more information about these type of EWS errors, see EWS Response Codes.

Resolution

If the false negative emails cannot be submitted using the Outlook email submission add-in, these emails would need to be reported manually.

Submit false positives for legitimate email flagged as spam

Submit false negatives for email not flagged as a threat

Additional Information

NOTE: Microsoft Exchange Server 2013 was an on-premises email and calendar server software that has reached its official end of support, with support ending on April 11, 2023

Also, Microsoft Exchange Server 2016 is an email and calendaring server that is reaching its end of support on October 14, 2025, meaning it will no longer receive security updates or technical support.