CkPython

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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import sys
import chilkat

success = 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.

mailman = chilkat.CkMailMan()

#  Configure the SMTP server connection.
mailman.put_SmtpHost("smtp.example.com")
mailman.put_SmtpPort(465)
mailman.put_SmtpSsl(True)
mailman.put_SmtpUsername("user@example.com")
mailman.put_SmtpPassword("myPassword")

#  Explicitly open (and authenticate) the SMTP connection.

success = mailman.OpenSmtpConnection()
if (success == False):
    print(mailman.lastErrorText())
    sys.exit()

print("SMTP connection opened.")

#  ... send one or more emails here ...

#  Close the connection when done.
success = mailman.CloseSmtpConnection()
if (success == False):
    print(mailman.lastErrorText())
    sys.exit()