Simple Sendmail With CDO

This code is working partially fine

<%
sch = "http://schemas.microsoft.com/cdo/configuration/"
Set cdoConfig = Server.CreateObject("CDO.Configuration")
cdoConfig.Fields.Item(sch & "sendusing") = 2
cdoConfig.Fields.Item(sch & "smtpserver") = "mail.aws.no"
cdoConfig.fields.update

Set cdoMessage = Server.CreateObject("CDO.Message")
Set cdoMessage.Configuration = cdoConfig
cdoMessage.From = Request.Form("E-Mail")
cdoMessage.To = Request.Form("sendto")
cdoMessage.Subject = "Tilbakemelding fra nettsiden"
cdoMessage.TextBody = strBody
cdoMessage.Send
Set cdoMessage = Nothing
Set cdoConfig = Nothing
Response.redirect Request.form("resulturl")
%>

Well, this works with only some addresses and not others.

Examples:

bjorn@domain.no
b@2.com

will work...

On the other hand:

bjorn.kaa@domain.no
bjorn-kaa@domain.no

won't work at all...