This question applies Barracuda Spam Firewall models 300 and above, all firmware versions.
Because the New User Quarantine State option on the Basic > Quarantine page is set to No. If this is set to Yes, user quarantine accounts will be created automatically when messages for those users are classified as quarantine. Quarantine boxes for invalid users will not be created if your recipient verification is blocking invalid recipient messages.
On earlier versions of the Spam Firewall firmware, there was the potential for both the Linked Domains and Unify Email Aliases features to be configured at the same time. Circumstances when both of these configurations are enabled can cause aberrant behavior with the creation of new user accounts. In the event that attempts to both automatically and manually create a user that exists on a domain fail, ensure that the Linked Domain configuration under Basic -> Quarantine is not enabled. This configuration causes any user account created to maintain the local part of the email address, but replace the domain portion with what is configured under Basic -> IP Configuration as the default domain. With multiple domain occupancy on an appliance, this configuration may not be the intended behavior.
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