Function MassIM
{
    Try
    {
        $Excel = New-Object -ComObject Excel.Application
        $Excel.Visible = $False
    }
    Catch [System.Exception]
    {
        $TS = TimeStamp
        "${TS}:Could not load Excel." | OutputToError
        Throw FatalError
    }

    Try
    {
        $IMBook = $Excel.Workbooks.Open("C:\IMList.xls")
    }
    Catch [System.Exception]
    {
        $TS = TimeStamp
        "${TS}:Could not open required workbook." | OutputToError
        Throw FatalError
    }

    Try
    {
        $IMSheet = $IMBook.Worksheets.Item(1)
    }
    Catch [System.Exception]
    {
        $TS = TimeStamp
        "${TS}:Could not open required worksheet." | OutputToError
        Throw FatalError
    }

    Try
    {
        $AssemblyPath = “C:\Program Files (x86)\Microsoft Lync\SDK\Assemblies\Desktop\Microsoft.Lync.Model.DLL”
        Import-Module $AssemblyPath
    }
    Catch [System.Exception]
    {
        $TS = TimeStamp
        "${TS}:Could not load required DLL files" | OutputToError
        Throw FatalError
    }

    Try
    {
        $LyncClient = [Microsoft.Lync.Model.LyncClient]::GetClient()
    }
    Catch [System.Exception]
    {
        $TS = TimeStamp
        "${TS}:Could not connect to Lync client." | OutputToError
        Throw FatalError
    }

    $FoundEmptyCell = $False
    $Row = 1

    While (!$FoundEmptyCell)
    {
        If ($IMSheet.Cells.Item($Row, 1).Value() -EQ $null)
        {
            $FoundEmptyCell = $True
        }
        Else
        {
            Try
            {
                $User = $IMSheet.Cells.Item($Row, 1).Value()
                $UserDesk = $IMSheet.Cells.Item($Row, 2).Value()
                $UserExt = $IMSheet.Cells.Item($Row, 3).Value()
            }
            Catch [System.Exception]
            {
               $TS = TimeStamp
               "${TS}:Could not load data from worksheet." | OutputToError
               Throw FatalError
            }
            $User = $User -split ','
            $UserName = $User[1] + "." + $User[0] + "@user.com"
            $UserName.Trim()

            Try
            {
                $Convo = $LyncClient.ConversationManager.AddConversation()
                $MSG = New-Object "System.Collections.Generic.Dictionary[Microsoft.Lync.Model.Conversation.InstantMessageContentType,String]"
                $MSG.Add(0, "Hello ${UserName}. Is your desk still ${UserDesk}? Is your extension still ${UserExt}?")
                $null = $Convo.AddParticipant($UserName)
            }
            Catch [System.Exception]
            {
               $TS = TimeStamp
               "${TS}:Could not initiate conversation." | OutputToError
               Throw FatalError
            }

            Try
            {
                $Mod = $Convo.Modalities[1]
                $null = $Mod.BeginSendMessage($MSG, $null, $MSG)
            }
            Catch [System.Exception]
            {
               $TS = TimeStamp
               "${TS}:Could not instant message${UserName}." | OutputToError
               $Error | OutputToError
            }
            $Row++
        }
    }

$Excel.Quit()
}