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Installing the Gmail Add-on
The Gmail Add-on is a side-panel that lives directly inside Gmail. Unlike the SGN Chrome extension (which only runs in Chrome on a desktop), the add-on works wherever Gmail does — Gmail on the web and the Gmail mobile app. It allows you to both read and write notes on the email you are currently viewing.
The add-on is a paid feature (basic CRM subscription or higher). This page covers how to install it and what to expect.
Before you install
  • Ensure you have an active paid Simple Mobile CRM subscription on the Google account you plan to use.
  • Ensure that Google account is signed into Gmail (web or mobile).
💡 Add-ons are tied to a single Google account at install time. If you use multiple Google accounts in your browser, make sure you are signed into the right one before you install — otherwise, the add-on won't appear on the inbox you actually use.
Step 1 — Install from Google Workspace Marketplace
  1. Open the Google Workspace Marketplace listing for Simple Mobile CRM.
  2. Click Install.
  3. Choose the Google account you want the add-on installed on. Confirm it matches your paid CRM account.
  4. Review and accept the permissions Google requests.
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Step 2 — Find the side panel in Gmail
On desktop (Gmail web)
  1. Open Gmail in your browser.
  2. Open any email.
  3. Look in the right-hand side panel. You should see the Simple Mobile CRM icon in the vertical icon strip.
  4. Click the icon to open the add-on.
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Step 3 — Sign in to the add-on on desktop (required even if you only use the add-on on a mobile device)
The first time you open the add-on, you will be asked to authorize Simple Mobile CRM. This is what links the add-on to your paid CRM account. After you authorize, you should see your note for the open email (or an empty editor if there isn't one yet). 

If you encounter a 'permission denied' error during this step, you can use a Chrome Guest window to complete the sign-in. Please see the troubleshooting section for more details.
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Step 4 — View the note on Gmail app
On mobile (the Gmail app)
  1. Open the Gmail app on your phone.
  2. Open any email.
  3. Scroll to the bottom of the email view to find the "Available add-ons" row.
  4. Tap Simple Mobile CRM. (You don't need to sign in again if you have already signed in on desktop.)

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What you can do with the add-on
  • Read the note attached to the email you're currently viewing.
  • Write or edit that note. Changes sync back to your CRM and to the other places notes appear (Mobile App, CRM Website, SGN extension on desktop).
  • See basic context about the sender and thread.
What it can't do (Google limitation): Show note labels in your inbox list. Add-ons only see the currently open message, so they cannot decorate the message list view. If inbox-list visibility matters to you, install the SGN Chrome extension on your desktop as well.
Troubleshooting
The add-on isn't showing up in Gmail.
  • Refresh / reload Gmail. New add-on installs sometimes only appear after a hard reload.
  • Confirm you installed it on the same Google account you're currently using in Gmail.
The add-on says "permissions missing" or loops the sign-in prompt. This is our most common install issue, often called the Chrome Profile Pitfall.
Why it happens: Even though the add-on lives inside Google Workspace (not as a Chrome extension), having multiple Google accounts logged into the same Chrome profile simultaneously can confuse Google's OAuth system when you try to authorize the add-on.
  • The Quick Fix: Open a Chrome Guest Window (click your profile icon in Chrome -> "Guest"). Log into your primary Gmail account here and authorize the add-on. Since the Guest window is completely isolated, it prevents the multi-account confusion. Note: You only need the Guest window for the authorization step; once the add-on is authorized, it will work normally in your standard Chrome profile and the Gmail mobile app too.
  • The Permanent Fix: If you frequently use multiple Google accounts on one computer, we highly recommend creating a fresh, dedicated Chrome profile for your primary work account rather than logging multiple accounts into one browser window.
It worked before, now it doesn't open.
  • Confirm your paid subscription is still active (access stops when the subscription lapses).
  • Try removing and reinstalling the add-on on the correct Google account.
Quick answers
Does the add-on work on the Gmail mobile app? Yes. That is its main advantage over the SGN Chrome extension, which is desktop-only.
Do I need both the add-on and the SGN Chrome extension? Most people use one at a time. SGN gives you inbox-list note labels on desktop; the add-on gives you a native side panel on desktop and mobile. Power users often install both.
Can I install the add-on on more than one Google account? Yes. Install it separately on each account. Each install is independent and authorizes against that account's CRM membership.