All Barracuda Spam Firewalls that support LDAP verification, all firmware versions.
Check to see whether the domain for which unwanted quarantine account are created is configured to use standard LDAP verification (Domains > Edit Domain). Unify Email Aliases will have no effect if Exchange Accelerator/LDAP Verification is set to No.
In this case, the Barracuda will contact the destination SMTP server and, if that particular email address is verified, it will create a quarantine account (if Per-User quarantine has been enabled).
From the online Barracuda documentation:
"Unify Email Aliases - Whether or not the Barracuda Spam Firewall performs account unification (also known as alias linking). If set to Yes, the Barracuda Spam Firewall will attempt to gather the primary email address and UID (using LDAP) for the addressee of the email it has just received. "
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