Adding Users: Explicit vs. SMTP Discovery -
Go to Email Protection tab > Setup tab > User Creation Settings > set User Creation Mode to "Explicit" > and Set When a Recipient is Invalid to "Do nothing".
The User Creation Settings window allows you to configure the method that is used to create user accounts (a.k.a. email addresses) in Email Protection and to designate an action for when the recipient email address is invalid or nonexistent. Use these options to designate the desired action to be taken when an email has an invalid recipient address. Valid values are the following:
User Creation Radio Buttons explained:
- SMTP Discovery - This option designates that users will be created (and deleted) automatically based on SMTP transactions. In this mode, a user account is automatically created when several messages have been successfully delivered to a recipient who does not already have a user account. The number of delivered messages required to trigger a user creation event varies due to system-related factors. Only messages delivered to recipient email addresses in a primary domain are counted for the purpose of user creation. Messages sent to recipient email addresses in alias domains are not counted.
- Explicit - This option designates that only the manual creation and deletion methods are enabled in Email Protection. If Email Protection receives an email that does not have an existing user account, it will perform the action designated in the When a Recipient is Invalid area.
When a Recipient is Invalid explained:
- Accept and silently discard the message: The email is accepted, but is discarded without notification.
- Deny delivery: The email is denied delivery.
- Do nothing: The email is denied delivery if the Customer's MTA permfailed the email as invalid recipient and the user creation method is set to Explicit.