Why is CDO message not getting out to external addresses?

I have an HTML form which solicits data and then passes it to an ASP page which formats and e-mails data out.  It works GREAT with internal addresses within our company.  As soon as I try to send to an external address, or mobile device, the whole thing crashes and I get:

error '8004020f'
/form/CMS/lean/hitCount/send_notice.asp, line 46

Line 46 is my mail.Send line

Why can't I send out??

Please see code below:

    <%
        when = Request.Form("when")
        what = Request.Form("S_event")
        where = Request.Form("line_name")
        why = Request.Form("why")
        message="At " &when & " an " &what & " for the " &where & " line due to " &why
       
       
        set cdoConfig = CreateObject("CDO.Configuration")
        with cdoConfig.Fields
            .Item ("http://schemas.microsoft.com/cdo/configuration/sendusing")=2
            .Item ("http://schemas.microsoft.com/cdo/configuration/smtpserver")="xxx.yyy.com"
            .Item ("http://schemas.microsoft.com/cdo/configuration/smtpserverport")=25
            .Update
        end with
       
        set myMail=CreateObject("CDO.Message")
        with myMail
            set .Configuration = cdoConfig
            .From="fake_address@mycompany.com"
            .Subject="Safety Notification"
            .To="phone_number@carrier.net"
            .TextBody=message
            .Send  
        end with
       
        set myMail = nothing
    %>