Recieving Access denied - Invalid HELO name

Asked by:
penton6 / 16 Points
2012-09-06 11:31 pm EST
Email Troubleshooting
On 04-Sept-2012 the code you see below was executing error free. Today on 06-Sept-2012 it now generates the error message "Recieving Access denied - Invalid HELO name". I have read your 550 access denied article and understand what you are saying. However in this specific case I have a simple SMTP client executing in code using the Microsoft Net.Mail.SmtpClient class library. I cannot see how to get around this problem through any code changes. Any suggestions (not necessarily to the code) but otherwise?

Private Sub btnSend_Click(sender As Object, e As System.EventArgs) Handles btnSend.Click

mail = New Net.Mail.MailMessage()


'create the mail message
Mail.IsBodyHtml = False

'set the addresses
mail.From = New Net.Mail.MailAddress(tbFrom.Text)

'set the content
mail.Subject = tbSubject.Text
mail.Body = tbMSGBody.Text
mail.DeliveryNotificationOptions = Net.Mail.DeliveryNotificationOptions.OnFailure

If chkMap.Checked Then
Dim a As New Mail.Attachment(tbSnapshot.Text)
End If

'send the message - currently fails
smtp = New Net.Mail.SmtpClient("")

smtp.Port = 587
smtp.EnableSsl = False

smtp.DeliveryMethod = Net.Mail.SmtpDeliveryMethod.Network
smtp.UseDefaultCredentials = False

'to authenticate we set the username and password properites on the SmtpClient
smtp.Credentials = New Net.NetworkCredential(tbFrom.Text, tbPassword.Text)


btnCancel.Enabled = True
AddHandler smtp.SendCompleted, AddressOf SendCompletedCallback

Dim userState As String = "test message1"
smtp.SendAsync(mail, userState)

Catch ex As Exception

End Try

End Sub

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16,266 Points
2012-09-07 9:35 am EST
Hello penton6,

Typically this error occurs when an email client is not authenticating with the SMTP server. The sender will want to ensure they have the SMTP authentication setting activated within their email client. In this case, it may need additional code settings and variables (for email account username and password) in the code to do the SMTP authentication check.

For more information, see our full guide 550 Access denied - Invalid HELO name.

Best Regards,
Scott M

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