Public/Gmail/Get-GSGmailForwardingAddress.ps1

function Get-GSGmailForwardingAddress {
    <#
    .SYNOPSIS
    Gets Gmail forwarding address information for the user
    
    .DESCRIPTION
    Gets Gmail forwarding address information for the user
    
    .PARAMETER ForwardingAddress
    The forwarding address you would like to get info for. If excluded, gets the list of forwarding addresses and their info for the user
    
    .PARAMETER User
    The user to get the forwarding addresses for

    Defaults to the AdminEmail user
    
    .EXAMPLE
    Get-GSGmailForwardingAddress

    Gets the list of forwarding addresses for the AdminEmail user
    #>

    [cmdletbinding()]
    Param
    (
        [parameter(Mandatory = $false,ValueFromPipelineByPropertyName = $true)]
        [Alias("Id")]
        [string[]]
        $ForwardingAddress,
        [parameter(Mandatory = $false,Position = 0,ValueFromPipelineByPropertyName = $true)]
        [Alias("PrimaryEmail","UserKey","Mail")]
        [ValidateNotNullOrEmpty()]
        [string]
        $User = $Script:PSGSuite.AdminEmail
    )
    Begin {
        if ($User -ceq 'me') {
            $User = $Script:PSGSuite.AdminEmail
        }
        elseif ($User -notlike "*@*.*") {
            $User = "$($User)@$($Script:PSGSuite.Domain)"
        }
        $serviceParams = @{
            Scope       = 'https://www.googleapis.com/auth/gmail.settings.basic'
            ServiceType = 'Google.Apis.Gmail.v1.GmailService'
            User        = $User
        }
        $service = New-GoogleService @serviceParams
    }
    Process {
        try {
            if ($ForwardingAddress) {
                foreach ($fwd in $ForwardingAddress) {
                    $request = $service.Users.Settings.ForwardingAddresses.Get($User,$fwd)
                    Write-Verbose "Getting Forwarding Address '$fwd' for user '$User'"
                    $request.Execute() | Select-Object @{N = 'User';E = {$User}},*
                }
            }
            else {
                $request = $service.Users.Settings.ForwardingAddresses.List($User)
                Write-Verbose "Getting Forwarding Address List for user '$User'"
                $request.Execute() | Select-Object -ExpandProperty ForwardingAddresses | Select-Object @{N = 'User';E = {$User}},*
            }
        }
        catch {
            $PSCmdlet.ThrowTerminatingError($_)
        }
    }
}