Implementing domain-wide email signatures using Gmail API

Other Questions Gmail
1

Hey everyone,

I’m trying to set up custom signatures for all users in my Google Apps domain. I want each signature to show the user’s name and job title. After some digging, I found out the Gmail API might be the way to go.

I’ve managed to get a list of all domain users with their email, name, and job title. Now I’m stuck on actually setting the signatures. Here’s what I’ve tried:

function updateSignature(userEmail, userName) {
  const request = gapi.client.gmail.users.settings.sendAs.update({
    'userId': userEmail,
    'sendAsEmail': userEmail,
    'signature': `<b style="color: #4285f4;">${userName}</b>`
  });

  request.execute(response => console.log(response));
}

This works fine for my own email, but for other users, I get a ‘Delegation denied’ error. I’m a super admin, so I’m not sure why this is happening.

I’ve also tried using a service account, but I’m getting a ‘Login Required’ error. I thought service accounts didn’t need to log in?

Can anyone help me figure out how to authenticate properly and set these signatures for all users? Thanks!

2

I’ve dealt with similar challenges before. The issue you encountered often results from not having enabled domain-wide delegation for your service account. Even with super admin rights, you must go into the Google Workspace Admin Console, access the security settings, and assign your service account’s client ID along with the necessary Gmail API scopes. Once you have properly configured those settings, the errors like ‘Delegation denied’ and ‘Login Required’ should be resolved. Using batch processing for multiple updates also helps improve efficiency.

3

Your approach is on the right track, but there’s a crucial step you’re missing. For domain-wide operations, you need to use a service account with domain-wide delegation enabled. This allows you to impersonate users and make API calls on their behalf.

Here’s what you should do:

  1. Create a service account in Google Cloud Console
  2. Enable domain-wide delegation for this account
  3. In your Google Workspace admin console, authorize the service account with the necessary scopes

Once that’s set up, you’ll need to use the google-auth-library to create a JWT client. This client can then be used to make authenticated requests to the Gmail API for each user.

Remember to implement error handling and respect API quotas to avoid issues when updating signatures for many users.

4

hey mate, i had similar issue. u need to enable domain-wide delegation for ur service account. go to admin console, security settings, and add the service account client ID with gmail API scopes. that should fix the ‘Delegation denied’ error. also, try using batch requests to update multiple signatures at once. its way faster!