To allow connections only from DuoCircle Cloud IPs within Office 365 – Exchange Online you will need to create an Inbound Connector that is restricted to DuoCircle Cloud IPs. This is not covered by this example.

From within the Exchange Admin Center.

1.       Select mail flow

2.       Select connectors

3.       Click the plus sign to add a new Inbound connector

Within the new inbound connector properties give the connector a name eg. (DuoCircle Cloud IPs).

In the Sender IP address field click the plus sign to start entering IPs. 

The list of IP's are here -


     -When prompted for a username and password please enter an O365 Admin Credentials
    -Inbound Connector created will be disabled by default.

 #> Set-ExecutionPolicy RemoteSigned -Force

$UserCredential = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session

New-InboundConnector -Enable $False -Name "DuoCircle Cloud IP Ranges" -SenderDomains *  -RestrictDomainsToIPAddresses $true  -RequireTls  $false -SenderIPAddresses,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,