Authorization scopes for Gmail add-ons

Users must authorize add-ons and other applications that access their data or act on their behalf. When a user runs an add-on for the first time, the add-on UI presents an authorization prompt to start the authorization flow.

During this flow, the prompt tells the user what the application wants permission to do. For example, an add-on might want permission to read the user's Google Sheets or create events in their calendar. The add-on's script project defines these individual permissions as OAuth scopes.

You declare scopes in your manifest using URL strings. During the authorization flow, Apps Script presents a human-readable description of the scope to the user. For example, your Gmail add-on might use the "Read current message" scope, which is written in your manifest as https://www.googleapis.com/auth/gmail.addons.current.message.readonly. During the authorization flow, an add-on with this scope asks the user to allow the add-on to: View your email messages when the add-on is running.

Viewing scopes

You can see the scopes your script project currently requires by doing the following:

Open the script project in the Apps Script editor.
In the menu, select File > Project properties.
Select the Scopes tab.

You can also view the script project's current scopes in the project manifest, under the oauthScopes property, but only if you have set those scopes explicitly.

Setting explicit scopes

Apps Script automatically determines what scopes a script needs by scanning its code for function calls that require them. For most scripts this is sufficient and saves you time, but for published add-ons you should exercise more direct control of the scopes.

For example, Apps Script might give an add-on script project the very permissive scope https://mail.google.com by default. When a user authorizes a script project with this scope, the project is granted full access to the user's Gmail account. For published add-ons, you must replace this scope with a more limited set that cover the add-on's needs and no more.

You can explicitly set the scopes your script project uses by editing its manifest file. The manifest field oauthScopes is an array of all scopes used by the add-on. To set your project's scopes, do the following:

View the scopes your add-on currently uses. Determine what changes need to be made, such as using a narrower scope.
Open your add-on's manifest file.
Locate the top-level field labeled oauthScopes. If it is not present, you can add it.
The oauthScopes field specifies an array of strings. To set the scopes your project uses, replace the contents of this array with the scopes you want it to use. For example, for a Gmail add-on you might have the following:
```
{
  ...
  "oauthScopes": [
    "https://www.googleapis.com/auth/gmail.addons.current.message.metadata",
    "https://www.googleapis.com/auth/userinfo.email"
  ],
  ...
}
```
Save the manifest file changes.

OAuth verification

Using certain sensitive OAuth scopes may require that your add-on go through OAuth client verification before you can publish it. For more information, see the following guides:

Restricted scopes

Certain scopes are restricted and subject to additional rules that help protect user data. If you intend to publish a Gmail or editor add-on that uses one or more restricted scopes, the add-on must comply with all the specified restrictions before it can be published.

Review the full list of restricted scopes before you attempt to publish. If your add-on uses any of them, you must comply with the Additional Requirements for Specific API scopes prior to publishing.

Gmail add-on scopes

There are a few scopes that were created specifically for Gmail add-ons to help protect user Gmail data. You must add these scopes explicitly to your add-on manifest, along with any others your add-on code require.

The following are scopes frequently used in conjunction with Gmail add-ons; the ones labeled Required must be added to your Gmail add-on manifest.

Be sure to also replace the very broad https://mail.google.com scope in your add-on with a narrower set of scopes that allow the interactions your add-on needs and no more.

Scope	Description
`https://www.googleapis.com/auth/gmail.addons.current.action.compose`	Required if the add-on uses compose action triggers. Allows the add-on to temporarily create new drafts messages and replies. See Composing draft messages for details; this scope is also often used with compose actions. Requires an access token.
`https://www.googleapis.com/auth/gmail.addons.current.message.metadata`	Grants temporary access to the open message's metadata (such as the subject or recipients). Does not allow reading of message content and requires an access token. Required if the add-on uses metadata in compose action triggers. For compose actions, this scope is required if a compose trigger needs access to metadata. In practice, this scope lets a compose trigger access recipient lists (to:, cc:, and bcc:) of a reply email draft.
`https://www.googleapis.com/auth/gmail.addons.current.message.action`	Grants access to the open message's content upon a user interaction, such as when a add-on menu item is selected. Requires an access token.
`https://www.googleapis.com/auth/gmail.addons.current.message.readonly`	Grants temporary access to the open message's metadata and content. Also grants access to the content of other messages in the open thread. Requires an access token.
`https://www.googleapis.com/auth/gmail.readonly`	Read any email metadata and content, including the open message. Required if you need to read information about other messages, such as when conducting a search query or reading an entire mail thread. This is a very broad Gmail scope and should only be used if absolutely necessary.

In addition, if your add-on uses other Apps Script services you may need to include additional scopes. In most cases you can let Apps Script detect these scopes and update the manifest automatically. When editing your manifest's scope list, do not remove any scopes unless you are replacing them with a more appropriate alternative, such as a narrower scope.

For reference, here is a list of Apps Script scopes that often are used in conjunction with Gmail add-ons:

Scope	Description
`https://www.googleapis.com/auth/userinfo.email`	Allows the project to learn the current user's email address.
`https://www.googleapis.com/auth/script.locale`	Allows the project to learn the current user's locale and timezone. See Accessing user locale and timezone for details.
`https://www.googleapis.com/auth/script.external_request`	Allows the project to make `UrlFetch` requests. This is also required if the project makes use of the OAuth2 for Apps Script library.

Access tokens

To protect user data, the Gmail add-on scopes only grant temporary access to user data. To enable this access, you must call the function GmailApp.setCurrentMessageAccessToken(accessToken) using an access token as an argument. You must obtain an access token from an action event object.

The following shows an example of setting an access token to allow access to a message's metadata. The only scope necessary for this example is https://www.googleapis.com/auth/gmail.addons.current.message.metadata.

function readSender(e) {
  var accessToken = e.messageMetadata.accessToken;
  var messageId = e.messageMetadata.messageId;

  // The following function enables short-lived acess to the current
  // message in Gmail. Access to other Gmail messages or data isn't
  // permitted.
  GmailApp.setCurrentMessageAccessToken(accessToken);
  var mailMessage = GmailApp.getMessageById(messageId);
  return mailMessage.getFrom();
}