Customers using the Advanced Account Administration Console can choose how emails to an unknown internal user are handled. An option called 'Unknown Address Type' is available in the Administration Console, allowing you to select whether messages to an unknown internal user are temporarily deferred, or rejected.
This option is only available on a Master account and you need to have Master Administrator permissions to change the setting.
To select how emails to an unknown internal user are handled:
- Log on to the Administration Console.
- Click on the Administration toolbar button. A drop down menu is displayed.
- Click on the Account | Account Settings menu item. The Account Settings tab is expanded by default.
- In the Unknown Address Type setting, select one of the following
- 451 Deferral: This is the default setting. If selected, emails to an unknown internal user are temporarily deferred with a 451 code. The sender can retry multiple times, allowing the Administrator an opportunity to synchronize the directory or create the user manually.
- 550 Rejection: If selected, and an email is sent to an unknown internal user, the sender will receive an "Invalid Recipient" code resulting in a Non-Delivery Report (NDR). The failed delivery information is then logged in Monitoring | Rejections in the Master account.
- Click on the Save button.