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Use cases → Email operations

Automate signature updates for every user in Workspace

Apply a standard email signature across all mailboxes using a delegated service account and track which users have been updated.

Who it is forIT admins and operations teams managing organisation-wide branding or compliance.
APIsGmail API, Admin SDK
Typical scopesgmail.settings.basic, admin.directory.user.readonly

The problem

Manual signature updates are ignored or outdated, especially after rebrands or regulatory changes. Central enforcement is needed, but the Gmail UI and standard admin controls cannot push updates at scale.

How it works

  1. Read the list of active users from the Directory API.
  2. Use domain-wide delegation to impersonate each user in turn.
  3. Call the Gmail API's 'SendAs' settings endpoint to set or update the signature.
  4. Record update status and any errors per user for reporting and retry.

What changes

All users receive the correct, up-to-date signature automatically, with a record of who was updated and which accounts failed.

The trap in this one. The Gmail API caches signature updates for up to an hour per user. If you attempt to set a signature twice in quick succession (for example, if the run is retried after a partial failure), the API may silently accept the call but not update the signature, leaving some users with stale branding. For idempotency, always compare the current signature before writing and log the API response body, not just the HTTP status.

Watch it explained

“Gmail Signature Management Tool | How to Change User Signatures” — HiView Solutions on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

Can this method update signatures for delegated or group mailboxes?

No, only user mailboxes are supported via user impersonation. Group or alias signatures are not exposed through the Gmail API.

How quickly do users see the new signature?

Changes usually appear within minutes, but Gmail clients can cache settings. Some users may not see updates until their client refreshes or next login.

Want this built?

This is a pattern we run in production. We will set up the delegation and build this on top of it — $500 per hour, most of it working the same day.

Talk to us Or read the setup guide

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