36ccb1df_Set_SenderIdConfig__Description
[Parameter] ExternalMailEnabled [Required] Optional [Type] System.Boolean [Description] 
Valid input for the ExternalMailEnabled parameter is $true or $false. The default setting is $true. When the ExternalMailEnabled parameter is set to $true, all messages from unauthenticated connections are passed through the Sender ID agent for processing.
Set-SenderIdConfig
Description