Email Error: Server Response Was Not Available

I found the below code in one of the posts and it was working fine uptill few days back. now, i get the error Run Time error '-2147220975(80040211) The message could not be sent to the SMTP server. The transport error code was 0x80040217. The server response was not available

Sub CDO_Send_Workbook()
Dim iMsg As Object
Dim iConf As Object
Dim wb As Workbook
Dim WBname As String
Application. ScreenUpdating = False
Set wb = ActiveWorkbook
WBname = wb. Name & " " & Format(Now, "dd-mm-yy h-mm-ss") & ".xls"
wb.SaveCopyAs "C:/" & WBname
Set iMsg = CreateObject("CDO.Message")
Set iConf = CreateObject("CDO.Configuration")
iConf.Load -1 ' CDO Source Defaults....................