Chilkat2-Python

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 chilkat2

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 = chilkat2.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):
    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()