VB.NET

Send an SMTP NOOP Command

Demonstrates the Chilkat MailMan.SmtpNoop method, which sends an SMTP NOOP command to the server. NOOP does nothing except elicit a positive response, which is useful for keeping a connection alive or verifying it is still responsive. This example opens an SMTP connection, sends a NOOP, and closes.

Background: When holding an SMTP connection open across many sends (see OpenSmtpConnection), an idle stretch can cause the server to time out and drop the socket. A periodic NOOP keeps the session active and confirms the server is still responding, so the next SendEmail doesn't fail on a silently-closed connection.

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Dim success As Boolean = False

'  Demonstrates the MailMan.SmtpNoop method, which sends an SMTP NOOP command to the server.
'  NOOP does nothing except elicit a positive response, useful for keeping a connection
'  alive or verifying it is still responsive.

Dim mailman As New Chilkat.MailMan

'  Configure the SMTP server connection.
mailman.SmtpHost = "smtp.example.com"
mailman.SmtpPort = 465
mailman.SmtpSsl = True
mailman.SmtpUsername = "user@example.com"
mailman.SmtpPassword = "myPassword"

'  Open the SMTP connection.

success = mailman.OpenSmtpConnection()
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


'  Send a NOOP to keep the connection alive.
success = mailman.SmtpNoop()
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


success = mailman.CloseSmtpConnection()
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("SMTP NOOP succeeded.")