File Blocking email notification is not sent when the user logon account and email address are not in the same format.
The [USER NO DOMAIN] variable, within the Notifications configuration for the file blocking rule, will use the logon name for that user. If that name does not match the format for the email address then the email will not be received by the user.
Logon account: user1
Email address: email@example.com or firstname.lastname@example.org
For the email to function properly the email address would have to be email@example.com.
Create an SMTP alias in Exchange for the user that matches the logon account format. In the above example the additional SMTP address would have to be firstname.lastname@example.org for the email to be sent to the user when the file is blocked.
This issue has been addressed as part of the following release:
Enterprise Vault 10.0.4 - Release Details