Asynchronously sending Emails in VB.net? - vb.net

Question

Public Async Function SendEmail(ByVal EmailToIds As String, ByVal Subject As String, ByVal Message As String, Optional ByVal EmailCcIds As String = "", Optional ByVal MailAttachment As String = "", Optional ByVal FromEmailType As Integer = 0, Optional EmailBccIds As String = "") As Task
Dim EmailPwd() As String
Dim FromEmail, Password As String
'Dim objSmtp As SmtpClient
Dim objMail As MailMessage
Dim objAttachment As Attachment
Try
EmailPwd = GetEmailPassword(FromEmailType).Split("|")
FromEmail = EmailPwd(0)
Password = EmailPwd(1)
objMail = New MailMessage
objMail.From = New MailAddress(FromEmail)
objMail.Subject = Subject
objMail.IsBodyHtml = True
objMail.Body = Message
objMail.To.Add(EmailToIds)
If Len(EmailCcIds) > 0 Then
objMail.CC.Add(EmailCcIds)
End If
If Len(EmailBccIds) > 0 Then
objMail.Bcc.Add(EmailBccIds)
End If
If MailAttachment <> "" Then
objAttachment = New Attachment(MailAttachment)
objMail.Attachments.Add(objAttachment)
End If
Using objSmtp = New SmtpClient()
objSmtp.Host = ConfigurationSettings.AppSettings("SmtpClient")
objSmtp.DeliveryMethod = SmtpDeliveryMethod.Network
objSmtp.UseDefaultCredentials = False
objSmtp.Credentials = New NetworkCredential(FromEmail, Password)
objSmtp.Port = 587
objSmtp.EnableSsl = True
ServicePointManager.ServerCertificateValidationCallback = Function(s As Object, certificate As X509Certificate, chain As X509Chain, sslPolicyErrors As SslPolicyErrors) True
Await objSmtp.SendMailAsync(objMail)
End Using
Catch ex As Exception
Throw Ex
End Try
End Function
Getting Error : Failure sending mail.
Please help me to do this.
Thank You So much in Advance.