ASP.net Emailing programmatically

Hi. I have the following information in my ASP.net web config file for sending emails using the VB.net code further down. For some reason this has just sopped working. Is there better code that I can use? Is there somewhere that I could perhaps test that these settings will in fact send an email?
Thanks

    <smtp from="noreply@thexxxx.com">
        <network host="mail.thexxx.com" port="587" userName="noreply@thexxx.com" password="xx" />
      </smtp>

    Public Function oSendMailMessage(ByVal from As String, ByVal recepient As String, ByVal bcc As String,
                                 ByVal cc As String, ByVal subject As String, ByVal body As String,
                                 ByVal blnUseHTML As Boolean) As String
        Try

            ' Instantiate a new instance of MailMessage
            Dim mMailMessage As New MailMessage()

            ' Set the sender address of the mail message
            mMailMessage.From = New MailAddress(from)
            ' Set the recepient address of the mail message
            mMailMessage.To.Add(New MailAddress(recepient))

            ' Check if the bcc value is nothing or an empty string
            If Not bcc Is Nothing And bcc <> String.Empty Then
                ' Set the Bcc address of the mail message
                mMailMessage.Bcc.Add(New MailAddress(bcc))
            End If

            ' Check if the cc value is nothing or an empty value
            If Not cc Is Nothing And cc <> String.Empty Then
                ' Set the CC address of the mail message
                mMailMessage.CC.Add(New MailAddress(cc))
            End If

            ' Set the subject of the mail message
            mMailMessage.Subject = subject
            ' Set the body of the mail message
            mMailMessage.Body = body

            ' Set the format of the mail message body as HTML
            If blnUseHTML = True Then
                mMailMessage.IsBodyHtml = True
            Else
                mMailMessage.IsBodyHtml = False
            End If

            ' Set the priority of the mail message to normal
            mMailMessage.Priority = MailPriority.Normal

            ' Instantiate a new instance of SmtpClient
            Dim mSmtpClient As New SmtpClient()
            ' Send the mail message
            mSmtpClient.Send(mMailMessage)
            oSendMailMessage = "Email Success!"
        Catch ex As Exception
            oSendMailMessage = "Email Not Sent! " & ex.Message
        End Try
    End Function