Open a Persistent SMTP Connection

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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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#include <C_CkMailMan.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkMailMan mailman;

    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 = CkMailMan_Create();

    //  Configure the SMTP server connection.
    CkMailMan_putSmtpHost(mailman,"smtp.example.com");
    CkMailMan_putSmtpPort(mailman,465);
    CkMailMan_putSmtpSsl(mailman,TRUE);
    CkMailMan_putSmtpUsername(mailman,"user@example.com");
    CkMailMan_putSmtpPassword(mailman,"myPassword");

    //  Explicitly open (and authenticate) the SMTP connection.

    success = CkMailMan_OpenSmtpConnection(mailman);
    if (success == FALSE) {
        printf("%s\n",CkMailMan_lastErrorText(mailman));
        CkMailMan_Dispose(mailman);
        return;
    }

    printf("SMTP connection opened.\n");

    //  ... send one or more emails here ...

    //  Close the connection when done.
    success = CkMailMan_CloseSmtpConnection(mailman);
    if (success == FALSE) {
        printf("%s\n",CkMailMan_lastErrorText(mailman));
        CkMailMan_Dispose(mailman);
        return;
    }



    CkMailMan_Dispose(mailman);

    }