# One-Click Setup for Gmail and Microsoft 365

Source: https://catalystgroup.gg/docs/email-delivery/one-click-setup/
Updated: 2026-10-20 · By Duane Garner

Connect Gmail or Microsoft 365 by signing in once, with no Google Cloud project or Entra app registration of your own.

One-Click Setup lets you connect the **Gmail** or **365 / Outlook** mailer by signing in to your Google or Microsoft account. CRM-NG keeps the connection renewed for you. You do not create an OAuth app, copy client IDs or paste secrets. This article is for administrators who want the quickest working email setup; the manual guides for [Gmail](https://catalystgroup.gg/docs/email-delivery/mailer-gmail/) and [Microsoft 365](https://catalystgroup.gg/docs/email-delivery/mailer-microsoft-365/) still apply if you prefer your own app.

 

## Where it is

 
- **Email Delivery → Mailer → Gmail** or **365 / Outlook**: the mode switch offers **One-Click** (sign in) or **Your own app** (the manual fields).
- **Settings → Run setup again → Email delivery**: the same **Sign in with Google** and **Sign in with Microsoft** buttons appear while CRM-NG SMTP Email is active.

 

One-Click Setup is part of CRM-NG Pro. On a site without it, the mode switch is not shown and the manual fields work as before.

 

## How it works

 
1. You click **Sign in with Google** or **Sign in with Microsoft**.
2. Your site sends you to the CRM-NG sign-in relay, which sends you on to Google or Microsoft. You sign in and allow **sending email as you**. That is the only permission asked for.
3. You come back to the screen you started from. The connection is stored on your site, sealed to your site's key, and the mailer is marked connected.
4. From then on your site renews the connection through the relay when it is about to expire. Email is sent directly from your site to Google or Microsoft; the relay never sees your messages.

 

The relay holds no copy of your sign-in. If your site cannot reach the relay at renewal time, it keeps using the current token until it expires and records a Debug Event.

 

## Sending identity

 

Mail is sent as the account you signed in with. With Gmail you can still send from an alias that account owns, see [Gmail: send from an alias](https://catalystgroup.gg/docs/email-delivery/mailer-gmail/). With Microsoft 365 the message goes out through `/me/sendMail` as the signed-in user.

 

## Switching off or changing accounts

 
- **Disconnect** on the mailer screen removes the stored connection. Sending stops until you connect again or switch the mode to **Your own app**.
- To change accounts, disconnect and sign in again with the other account.
- Site administrators can pin the relay address with the constant `CRMNG_SMTP_RELAY` or turn the feature off with `CRMNG_SMTP_ONE_CLICK` set to `false`; see [Secure settings with constants](https://catalystgroup.gg/docs/email-delivery/secure-settings-constants/).

 

## When something goes wrong

 

Each failure has its own article:

 
- [Sign-in relay unreachable](https://catalystgroup.gg/docs/email-delivery/error-one-click-relay-unreachable/)
- [Request refused by the relay](https://catalystgroup.gg/docs/email-delivery/error-one-click-relay-denied/)
- [Sign-in cancelled](https://catalystgroup.gg/docs/email-delivery/error-one-click-consent-denied/)
- [Sign-in could not be renewed](https://catalystgroup.gg/docs/email-delivery/error-one-click-token-refresh-failed/)