(Unicode C++) OAuth2 for a GMail using a P12 Service Account Key

See more GMail REST API Examples

Note: This example does not work for Personal Google Accounts where the email domain is @gmail.com

For more information, see https://www.chilkatsoft.com/google_workspace_setup_smtp_gmail.asp

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#include <CkHttpW.h>
#include <CkCertW.h>
#include <CkMailManW.h>
#include <CkEmailW.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkHttpW http;

    // --------------------------------------------------------------------------------
    // For a step-by-step guide for setting up your Google Workspace service account,
    // see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
    // --------------------------------------------------------------------------------
    // Begin by loading your Google service account key (.p12)
    CkCertW cert;
    bool success = cert.LoadPfxFile(L"c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12",L"notasecret");
    if (success != true) {
        wprintf(L"%s\n",cert.lastErrorText());
        return;
    }

    // The ISS is your service account email address ending in gserviceaccount.com.
    const wchar_t *iss = L"chilkatsvc@chilkat25.iam.gserviceaccount.com";

    // The scope is always the following string:
    const wchar_t *scope = L"https://mail.google.com/";

    // The sub is your company email address
    const wchar_t *oauth_sub = L"bob@yourcompany.com";

    // The access token is valid for this number of seconds.
    int numSec = 3600;

    const wchar_t *accessToken = http.g_SvcOauthAccessToken(iss,scope,oauth_sub,numSec,cert);
    if (http.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",http.lastErrorText());
        return;
    }
    else {
        wprintf(L"access token: %s\n",accessToken);
    }

    // The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.

    // -----------------------------------------------------------------------
    CkMailManW mailman;

    // Set the properties for the GMail SMTP server:
    mailman.put_SmtpHost(L"smtp.gmail.com");
    mailman.put_SmtpPort(587);
    mailman.put_StartTLS(true);

    mailman.put_SmtpUsername(L"bob@yourcompany.com");
    mailman.put_OAuth2AccessToken(accessToken);

    // Create a new email object
    CkEmailW email;

    email.put_Subject(L"This is a test");
    email.put_Body(L"This is a test");
    email.put_From(L"Bob <bob@yourcompany.com>");
    success = email.AddTo(L"Recipient",L"recipient@example.com");
    // To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

    success = mailman.SendEmail(email);
    if (success != true) {
        wprintf(L"%s\n",mailman.lastErrorText());
        return;
    }

    success = mailman.CloseSmtpConnection();
    if (success != true) {
        wprintf(L"Connection to SMTP server not closed cleanly.\n");
    }

    wprintf(L"Successfully sent email using Gmail with a service account key.\n");
    }