(PowerShell) 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 .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

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

$http = New-Object Chilkat.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)
$cert = New-Object Chilkat.Cert
$success = $cert.LoadPfxFile("c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12","notasecret")
if ($success -ne $true) {
    $($cert.LastErrorText)
    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.LastMethodSuccess -ne $true) {
    $($http.LastErrorText)
    exit
}
else {
    $("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 = New-Object Chilkat.MailMan

# Set the properties for the GMail SMTP server:
$mailman.SmtpHost = "smtp.gmail.com"
$mailman.SmtpPort = 587
$mailman.StartTLS = $true

$mailman.SmtpUsername = "bob@yourcompany.com"
$mailman.OAuth2AccessToken = $accessToken

# Create a new email object
$email = New-Object Chilkat.Email

$email.Subject = "This is a test"
$email.Body = "This is a test"
$email.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 -ne $true) {
    $($mailman.LastErrorText)
    exit
}

$success = $mailman.CloseSmtpConnection()
if ($success -ne $true) {
    $("Connection to SMTP server not closed cleanly.")
}

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