As a best practice, Sender ID should be configured in Exchange. Sender ID is configured correctly when the 'Enabled' and ...

As a best practice, Sender ID should be configured in Exchange. Sender ID is configured correctly when the 'Enabled' and 'ExternalMailEnabled' properties are set to true on SenderIDConfig object. You can use the Set-SenderIdConfig cmdlet to set the 'Enabled' and 'ExternalMailEnabled' properties to true. Visit www.microsoft.com/senderID for more information about Sender ID.