Barracuda Spam Firewall Model 300s, All firmware versions
Yes, multiple Barracuda Spam Firewall 300 systems can be deployed in a redundant fashion. Because these systems do not support clustering, there are special recommendations that should be followed to avoid creating multiple quarantine accounts for each user.
Select one Barracuda as the primary unit, and place it on main network. On the primary unit enable the Per-User Quarantine option, disable Tag scoring, and enable Quarantine scoring by specifying a Quarantine Score threshold value. Point the domain’s primary MX record at the public IP address that forwards the primary Barracuda.
Place the remaining Barracuda as the secondary unit on a failover network/NOC. Disable the Per-User Quarantine option (this is default), disable Quarantine scoring, and set the Tag score threshold value to match primary Barracuda's Quarantine score threshold value. Point the domain’s secondary MX record at the public IP address that forwards to the secondary Barracuda.
This will allow DNS to fail over to the secondary Barracuda only if the primary unit is unreachable. If this happens, the secondary Barracuda will "Tag" any messages that would have normally been quarantined by placing the text "[SPAM]" into the subject line of the email. This tagging is to prevent a second quarantine inbox from being created on the secondary Barracuda and causing confusion. Additionally, by having the secondary Barracuda installed at a remote or failover site, the secondary unit will be able to queue up emails until the main site is again reachable, even in the event of full network outage.
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