Error: The Transport Failed To Connect To The Server

I'm using this coding but get some error. i can't understand this line

.Item(sch & "smtpserver") = "<enter_mail.server_here>"

mail server means which server im used help me

error:Error Type:
CDO.Message.1 (0x80040213)
The transport failed to connect to the server.

<%
sch = "http://schemas.microsoft.com/cdo/configuration/"
Set cdoConfig = CreateObject("CDO.Configuration")
With cdoConfig.Fields
.Item(sch & "sendusing") = 2 ' cdoSendUsingPort
.Item(sch & "smtpserver") = "<enter_mail.server_here>"
.update
End With

Set cdoMessage = CreateObject("CDO.Message")
With cdoMessage
Set .Configuration = cdoConfig
.From = "basvbas@yahoo.com"
.To = "basvbas22@yahoo.com"
.Subject = "Sample CDO Message"
.TextBody = "This is a test for CDO.message"
.Send
End With

Set cdoMessage = Nothing
Set cdoConfig = Nothing
%>