ISSUEWhen using "Send an Email" action with a valid and active user in Office 365, the following error is occurred :
The message could not be delivered to one or more recipients
- Make sure that the email is valid and active user.
- Terminate and re-run the workflow.
- If the issue still persist, contact Nintex Support with the details of the email address so we can check in the log files.
- The issue is intermittent and only occurs in the period of time.
- The root cause is the email address has been soft blacklist by Nintex Mail Server provider because previously it tried to send an email with attachment greater than 20MB.