Check Send email with CDO 2000

>I have simple piece of code which does not work
>
>oMsg = createobject("CDO.Message")
>
>oMsg.To = "aa@bb.com"
>oMsg.Subject = "aaaaa"
>oMsg.AddAttachment("c:\autoexec.bat")
>oMsg.Send
>
>Return error code is
>
>OLE IDispatch exception code from ?:The message could not be sent to SMTP server.
>The transport error code was 0x80040217. The server response was not available.
>
>Any sugestion?
>
>Incoming mail server is IMAP.