(CkPython) 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

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux

import sys
import chilkat

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

http = chilkat.CkHttp()

# --------------------------------------------------------------------------------
# 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)
cert = chilkat.CkCert()
success = cert.LoadPfxFile("c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12","notasecret")
if (success != True):
    print(cert.lastErrorText())
    sys.exit()

# The ISS is your service account email address ending in gserviceaccount.com.
iss = "chilkatsvc@chilkat25.iam.gserviceaccount.com"

# The scope is always the following string:
scope = "https://mail.google.com/"

# The sub is your company email address
oauth_sub = "bob@yourcompany.com"

# The access token is valid for this number of seconds.
numSec = 3600

accessToken = http.g_SvcOauthAccessToken(iss,scope,oauth_sub,numSec,cert)
if (http.get_LastMethodSuccess() != True):
    print(http.lastErrorText())
    sys.exit()
else:
    print("access token: " + 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.

# -----------------------------------------------------------------------
mailman = chilkat.CkMailMan()

# Set the properties for the GMail SMTP server:
mailman.put_SmtpHost("smtp.gmail.com")
mailman.put_SmtpPort(587)
mailman.put_StartTLS(True)

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

# Create a new email object
email = chilkat.CkEmail()

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

success = mailman.SendEmail(email)
if (success != True):
    print(mailman.lastErrorText())
    sys.exit()

success = mailman.CloseSmtpConnection()
if (success != True):
    print("Connection to SMTP server not closed cleanly.")

print("Successfully sent email using Gmail with a service account key.")