Use the following steps to add the Barracuda IP ranges to your receive connector in Microsoft Office 365:
- Log in to the Office 365 admin center, and go to Admin centers > Exchange.
- In the left pane, click protection, and click connection filtering at the top of the page.
Click the + symbol, and in the add allowed IP address field, enter the first IP range to allow.
- Complete steps 3 and 4 for the remaining IP ranges.
- Click Save when you are done adding the Barracuda IP ranges.
Barracuda IP Ranges
Customers Using the US Barracuda Email Security Service Instance
US: 188.8.131.52/20 and 184.108.40.206/21
Customers Using UK Barracuda Email Security Service Instance
Customers Using DE (Germany) Barracuda Email Security Service Instance
/24 IP Ranges
Some Customers have reported that you can only add /24 IP ranges to the Office 365 setup as well as to some on-premise mail servers. You must add each range separately. For example, if you are a customer using the US Barracuda Email Security Service instance, you would add the following /24 IP ranges: