Email Workflow Error: The E-mail Message Cannot Be Sent. Make Sure The E-mail Has A Valid Recipient.

ISSUE

When running a workflow that is configured to send an email, the workflow suspends with the following error:

 

RequestorId: 6fdb72dd-529e-e60f-0000-000000000000. Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.ApplicationException: HTTP 400 {"error":{"code":"-2130242040, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"The e-mail message cannot be sent. Make sure the e-mail has a valid recipient."}}}

ERROR CODE

RequestorId: 6fdb72dd-529e-e60f-0000-000000000000. Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.ApplicationException: HTTP 400 {"error":{"code":"-2130242040, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"The e-mail message cannot be sent. Make sure the e-mail has a valid recipient."}}}

RESOLUTION

When trying to send to an email that is not associated with an account within SharePoint Online, ensure that the Send An Email action is configured for 'External email and attachment'.