Listing in the Barracuda Blacklist could indicate any number of issues that need to be addressed in your network including but not limited to: virus-generated spam, poor server configuration, dynamic IP Addresses previously used by spammers, bulk mail sending that does not comply with the CAN-SPAM Act.
Barracuda Reports Sources Of Spam
Spam-based Blacklists are those that will list either single IP Addresses or entire ranges that have actually received Spam, i.e. Unsolicited Bulk Email (UBE) in their Spamtraps from an IP-Address. This could be a result of a compromised email account, an Open Relay, or simply sending mass emails / marketing and not following best practices according to the "CAN-SPAM Act of 2003" (ref: https://en.wikipedia.org/wiki/CAN-SPAM_Act_of_2003)
Barracuda Requires A Manual Delisting Request
This blacklist does support a manual request to remove or delist your IP Address from their database. Please note that removal requests that are submitted without addressing the core problem will likely result in your IP Address or Domain being relisted in that database, which can cause subsequent problems and extended listing periods without release.