Invalid Mail Address Gives Error In CDO Mail

I'm using CDO from my vb component to fire email. The problem is
whenever one of the email addresses in to, or cc is wrong then none of
the mails are fired even to the correct addresses. It gives an error
like

The server rejected one or more recipient addresses. The server
response was: 550 Relaying denied for <xfd@wre.com>

My code goes like this. Why is the mail server trying to look for the
validation of email ids??I want that atleast the mail should be fired
to the correct email addresses rather than no email fire. Can i
achieve that.

Dim iMsg As New CDO.Message
Dim iConf As New CDO.Configuration


With iConf
.Fields.Item(cdoSendUsingMethod) = cdoSendUsingPort
.Fields.Item(cdoSMTPConnectionTimeout) = 10 ' quick timeout
.Fields.Item(cdoSMTPAuthenticate) = cdoBasic
.Fields.Item(cdoSendUserName) = "username"
.Fields.Item(cdoSendPassword) = "password"
.Fields.Item(cdoURLProxyServer) = "server:80"
.Fields.Item(cdoURLProxyBypass) = "<local>"
.Fields.Item(cdoURLGetLatestVersion) = True
.Fields.Update
End With

Set iMsg.Configuration = iConf
With iMsg
.To = strToEmail
.From = strFromEmail
.CC = strCCEmail
.BCC = strBCCEmail
.Subject = strMailSubject
If strMailFormat = "TEXT" Then
.TextBody = strMailBody
Else
.HTMLBody = strMailBody
End If
If strAttachment <> "" Then
.AddAttachment strAttachment
End If
If intPriority = 2 Then
.Fields.Item("urn:schemas:mailheader:X-Priority") =
cdoHigh
.Fields.Update
End If

.Send
End With