Gmail add-on issues

The Gmail add-on lives in Google's environment, which means most issues come from Google Workspace policies, browser caches, or expired API keys. This page covers the most common ones.

Add-on doesn't appear after installing

You installed from the marketplace but don't see the EmailBuilder icon in Gmail.

Likely causes:

• The add-on is installed but Gmail hasn't picked it up yet (it can take a minute).
• The browser cached an older version of Gmail's UI.
• A Google Workspace admin policy is blocking third-party add-ons.

Fix:

1. Refresh Gmail (hard refresh: ⌘⇧R or Ctrl+Shift+R).
2. Click Compose. Look in the right-side add-on tray — the EmailBuilder icon should be there.
3. If still missing, sign out of Gmail and back in.
4. If still missing, check Google Workspace admin → Apps → Google Workspace Marketplace for any restrictions on third-party add-ons. Ask your IT/admin to allowlist EmailBuilder.

"Invalid API key" when connecting

You pasted a key but the add-on rejects it.

Likely causes:

• The key has a trailing space or was truncated when copying.
• The key was revoked or rotated after you copied it.
• You pasted a key from a different account.

Fix:

1. Sign in to app.emailbuilder.ai.
2. Account → Integrations → API Keys. Confirm the key you intended is listed and not revoked.
3. If it's been a while since you generated it, Generate new key and use the new one. Old keys can't be re-shown for security reasons.
4. Paste carefully — make sure there's no leading/trailing whitespace.

Keys begin with eb_ and are 67 characters long. Anything shorter was truncated when copying.

Connected, but my templates don't appear

The add-on shows the EmailBuilder UI, but the template list is empty or missing some templates.

Likely causes:

• The active project in your EmailBuilder account doesn't contain templates.
• The templates were created in a different project.
• The templates are tagged archived and the add-on filters them out.

Fix:

• In the add-on sidebar, click the project name (top of the panel) to switch projects.
• In EmailBuilder, verify templates exist in the current project at Templates.
• If templates are archived, untag them or use a fresh tag.

"Failed to insert" error in compose

You clicked Insert into draft and got an error.

Likely causes:

• The compose window was closed or reloaded between selecting the template and clicking Insert.
• The template contains a custom MJML element the add-on can't render to HTML (rare).
• A transient API hiccup.

Fix:

1. Close the error and click Insert into draft again.
2. If it persists, refresh Gmail and try again.
3. If a specific template fails consistently, the issue may be in the template's MJML. Test in EmailBuilder's editor — if preview there works, the template should insert.

Inserted HTML looks broken in compose

The template inserted but renders wrong in the Gmail compose window — wrong widths, missing styles, etc.

Why this happens:

Gmail's compose UI doesn't render the full email environment — it's a contenteditable div with its own CSS. Some MJML output (particularly inline styles on tables, media queries) is partially stripped or overridden.

The good news:

The actual sent email — whether sent from Gmail compose or any other path — uses the full HTML. The compose preview is a stripped-down approximation; the recipient sees the real thing.

Fix:

• Before sending, send a test to yourself via Gmail and open in a different inbox to verify the recipient experience.
• If the compose preview is misleading enough that it bothers you, use EmailBuilder's editor preview to confirm before inserting.

Add-on shows "Authentication expired — please reconnect"

The connection between Gmail and EmailBuilder broke.

Likely causes:

• The API key was revoked.
• You signed in with a different Google account that hasn't been linked.

Fix:

1. In the add-on, click the gear icon → Sign out (clears the local API key).
2. Sign back in by pasting your current API key from EmailBuilder.
3. If you have multiple Google accounts, make sure you're signed into the right one in Gmail before opening the add-on.

I'm signed into the wrong EmailBuilder account in Gmail

Each Google account can only be linked to one EmailBuilder account at a time.

Fix:

1. Click the gear icon → Sign out.
2. Generate an API key from the EmailBuilder account you want to link.
3. Paste it.

If you bounce between EmailBuilder accounts often (e.g. agency work), generate a named key per account and keep them in your password manager.

Add-on isn't showing for users in my Workspace

You installed the add-on for everyone in your domain, but some users don't see it.

Likely causes:

• Google Workspace add-on deployment can take up to 24 hours to propagate.
• The user's role/license doesn't permit add-ons.
• A category-level restriction (e.g. "block add-ons in Education licenses") is in place.

Fix:

• Wait 24 hours after first deploying.
• In Workspace admin → Apps → Google Workspace Marketplace → EmailBuilder, verify deployment scope and the affected user's organisational unit.
• For affected users: sign out of Google and back in to force a session refresh.

I want to uninstall

In Gmail:

1. Click the gear icon (Settings) → See all settings → Add-ons.
2. Find EmailBuilder → click Manage → Uninstall.

For a Workspace-wide install, the Workspace admin must uninstall from Workspace admin → Apps → Google Workspace Marketplace.

After uninstall, revoke the API key on the EmailBuilder side (Account → Integrations → API Keys) if you don't intend to reinstall.

Other issues

If your symptom isn't covered, email [email protected] with:

• A screenshot of the issue.
• Your account email.
• The Google account you're using in Gmail.
• The browser and OS.

We can usually reproduce common issues and ship a fix within a release.