Scope:
This solution applies to all Barracuda Spam Firewalls.
Answer:
During a firmware update, the Barracuda Spam Firewall will undergo a quick reboot.
During this time, the MTA (Mail Transfer Agent) will be restarted. If the MTA is not listening on port 25, a connecting server would receive a "Connection Refused". As a result, they would retry at their next scheduled retry interval (this is an independent value based on the sending server's configuration).
Additional Notes:
To control this process a little more, you could go to the Basic > Administration page and take the box offline (by clicking the Offline button) prior to upgrading the firmware. This will:
- Help make sure mail does not get lost.
- Speed up the upgrade process.
Link to This Page:
https://campus.barracuda.com/solution/50160000000GSg6AAG