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Use casesAdmin and governance

Update Gmail signatures for every user at once

Roll out company-wide signature changes using a delegated service account to enforce consistency and branding.

Who it is forIT administrators responsible for email branding and compliance.
APIsGmail API
Typical scopesgmail.settings.basic

The problem

Manual signature updates are ignored, leading to inconsistent branding and missing legal text. Central enforcement requires direct API calls per user, which can hit rate limits and obscure partial failures.

How it works

  1. Fetch the full user list from the directory.
  2. Authenticate with a service account using domain-wide delegation.
  3. For each user, call users.settings.sendAs.patch to update their signature.
  4. Log all responses, including errors and skipped accounts.
  5. Optionally trigger a notification to users about the change.

What changes

All users receive the updated signature without relying on manual action, and administrators have a record of which accounts were updated.

The trap in this one. The Gmail API’s sendAs.patch call is eventually consistent: changes may not appear in the user's UI for several minutes, and users with multiple aliases require patching each sendAs address separately. If you only patch the primary address, replies from secondary aliases will keep the old signature, leading to inconsistent outbound mail.

Watch it explained

UMS Bulk Email Signature Google Workspace Add-on – OAuth Scope Usage & Verification Demo” — UMS Tech Labs on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

How do I handle users with multiple aliases?

Enumerate all sendAs addresses for each user and patch each one; the API does not update them in bulk.

What if a user is suspended or has no mailbox?

The API will return an error; log these cases for follow-up but do not retry indefinitely.

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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