Generates the metalogix xml file using the raw LoginName and Email values for users stored in the target SharePoint site.

BasicMetalogixUserMappingXml.ps1

Add-PSSnapin Microsoft.SharePoint.PowerShell

function ConvertTo-MetalogixUserMappingXml
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][object[]]$Mapping
    )
    
    begin
    {
        $xml = New-Object System.Text.StringBuilder
        
        $xml.AppendLine( "<Mappings>" ) | Out-Null
    }
    process
    {
        foreach( $map in $Mapping )
        {
            $xml.AppendLine( "<Mapping Source=`"$($Mapping.Source)`" Target=`"$($Mapping.Target)`" />" ) | Out-Null
        }
    }
    end
    {
        $xml.AppendLine( "</Mappings>" ) | Out-Null

        return $xml.ToString()
    }    
}

Get-SPSite -Identity "https://sharepoint.2016.contoso.com/sites/teamsite" | 
    SELECT -ExpandProperty RootWeb | 
        SELECT -ExpandProperty SiteUsers | ? { -not [string]::IsNullOrEmpty($_.Email) } |
                SELECT @{Name="Source"; E={ $_.UserLogin}}, @{Name="Target"; E={$_.Email}} |
                    ConvertTo-MetalogixUserMappingXml | 
                        Set-Content -Encoding UTF8 -Path "MappingFile_$(Get-Date -Format FileDateTime).xml"