VB.NET

Open a Persistent SMTP Connection

Demonstrates the Chilkat MailMan.OpenSmtpConnection method, which explicitly opens a connection to the SMTP server and authenticates if a username and password, OAuth2 token, or other applicable settings have been provided. This example opens the connection, notes where sending would occur, and closes it.

Background: By default, sending a single email opens a connection, sends, and closes it. When sending many messages, that per-message overhead adds up. Explicitly calling OpenSmtpConnection once, sending in a loop, then CloseSmtpConnection keeps a single authenticated session open for the whole batch — substantially faster and gentler on the server than reconnecting each time.

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Dim success As Boolean = False

'  Demonstrates the MailMan.OpenSmtpConnection method, which explicitly opens a connection
'  to the SMTP server and authenticates if credentials (or an OAuth2 token) have been
'  provided.

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"

'  Explicitly open (and authenticate) the SMTP connection.

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


Debug.WriteLine("SMTP connection opened.")

'  ... send one or more emails here ...

'  Close the connection when done.
success = mailman.CloseSmtpConnection()
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If