mkornatz · December 4, 2017 15:05 · Dec 4, 2017
diff --git a/update-emails.js b/update-emails.js
@@ -0,0 +1,114 @@
+/**
+ * Set email signature on provided email addresses
+ * To ensure signatures have been successfully updated, follow the steps below:
+ *
+ * 1. Add comma-separated email addresses (example: '[email protected]', '[email protected]', '[email protected]')
+ * 2. Navigate to Run > setAllSignatures
+ * 3. Navigate to View > Logs
+ * 4. View log output "Signature successfully updated for [email address]"
+ */
+function setAllSignatures() {
+  var signatureTemplate = getTemplate('Signature');
+
+  var allSignatures = [  
+    '[email protected]'
+  ];
+
+  if (allSignatures.length > 0) {
+    for(var i in allSignatures) {
+      setSignature(allSignatures[i], signatureTemplate);
+    }
+  } else {
+     Logger.log("Oops, you need to specify an email address");
+  }
+}
+
+/**
+ *
+ *
+ *
+ *
+ *
+ * Helper Functions (below) - Do Not Run 
+ *
+ *
+ *
+ *
+ *
+ */
+
+/**
+ * Get the proper authorization from service account
+ * More information on service account at https://console.developers.google.com
+ *
+ * @param email {String} email address to be updated
+ */
+function getOAuthService(email) {
+  var OAUTH2_SERVICE_ACCOUNT_PRIVATE_KEY  = '-----BEGIN PRIVATE KEY-----\nMIIE...=\n-----END PRIVATE KEY-----\n';
+  var OAUTH2_SERVICE_ACCOUNT_CLIENT_EMAIL = 'email-signature-updater@email-signature-100000.iam.gserviceaccount.com';
+
+  // service identifier needs to change per user
+  return OAuth2.createService("Email Signature Updater - " + email)
+  .setTokenUrl('https://accounts.google.com/o/oauth2/token')
+  .setPrivateKey(OAUTH2_SERVICE_ACCOUNT_PRIVATE_KEY)
+  .setIssuer(OAUTH2_SERVICE_ACCOUNT_CLIENT_EMAIL)
+  .setSubject(email)
+  .setPropertyStore(PropertiesService.getScriptProperties())
+  .setScope('https://www.googleapis.com/auth/gmail.settings.basic')
+  .setParam('access_type', 'offline');
+}
+
+/**
+ * Reset the authorization state, so that it can be re-tested.
+ */
+function resetService(email) {
+  getOAuthService(email).reset();
+}
+
+/**
+ * Get the contents of an HTML template
+ *
+ * @param name {String} Name of HTML file
+ * @return {String} HTML string
+ */
+function getTemplate(name) {
+  return HtmlService.createHtmlOutputFromFile(name).getContent();
+}
+
+/**
+ * Call out to Gmail API to set email signature on given address
+ *
+ * @param userEmail {String} email address to be updated
+ * @param signature {String} HTML string used for signature template
+ */
+function setSignature(userEmail, signature) {
+  // Reset the service so we can reuse it
+  resetService(userEmail);
+
+  var params = {signature: signature},
+      service = getOAuthService(userEmail),
+      url = 'https://content.googleapis.com/gmail/v1/users/' + encodeURIComponent(userEmail) + '/settings/sendAs/' + encodeURIComponent(userEmail) + '?alt=json';
+
+  if (service.hasAccess()) {
+    var response = UrlFetchApp.fetch(url, {
+      method: 'PATCH',
+      muteHttpExceptions: true,
+      contentType: 'application/json',
+      payload: JSON.stringify(params),
+      headers: {
+        'Authorization': 'Bearer ' + service.getAccessToken()
+      }    
+    });
+
+    // error handling
+    if (response.getResponseCode() !== 200) {
+      Logger.log("ERROR: " + response.getContentText());
+    } else {
+      Logger.log("Signature successfully updated for " + userEmail + "!");
+    }
+
+  } else {
+     Logger.log(service.getLastError());
+  }
+
+}