Synchronizing User Accounts with G Suite

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In addition to adding users manually as described in chapter User Management, MailStore Server can synchronize its internal user database with the G Suite account of your organization.

During synchronization, user information, such as user names and email addresses, is copied from the G Suite account into MailStore Server's user database. That way, users can use their G Suite account credentials to also log on to MailStore Server and emails can be assigned to their corresponding user archives automatically, for example. No changes are made to the G Suite account itself by MailStore Server. The scope of the synchronization can be limited through filters.

Register Project with Google

Irregardless of whether own or third-party applications such as MailStore are supposed to interact with a G Suite account through Google APIs, they must be registered as a project with Google first. This is necessary to ensure that access by external applications is limited to a minimum and that each application uses its own set of credentials to authenticate itself.

Creating New Project

To register a project for MailStore with Google, proceed as follows:

  • Go to the Google Developers Console.
  • If prompted, login using a Google Account of you G Suite organization. A user with administrative privileges is highly recommend.
  • If no project exists, click Create on the dashboard. Otherwise open the Project drop-down list in the header bar and click New Project.
  • Name the project, e.g. MailStore Server. By default a random Project ID is assigned, which can be changed if desired.
  • Click on Create.
  • Once the project has been created, APIs & Services is shown.
  • Make sure that you have selected the newly created project. You can change the project by using the drop-down list.

Adding API Libraries

To specify which Google APIs are used by the application, proceed with the following steps:

  • Click on Library in the left navigation pane.
  • In the API Library, enable Admin SDK and Gmail API.
  • Return to the project's dashboard by clicking on Google APIs in the top navigation bar.

Customizing Consent Screen

A consent screen must exist before a domain-wide delegation of authority can be performed.

  • Click on OAuth consent screen in the left navigation pane.
  • Select Internal as User Type.
  • Click on Create
  • Fill in the an Application name, e.g. MailStore Server
  • Click on Save.

Creating Service Account

The following steps create a service account and its credentials which are used by MailStore to login to Google APIs.

  • Click on Credentials' in the left navigation pane.
  • Click + Create Credentials and select Service account from the drop-down list.
  • On the Create service account screen, enter a name for the service account. The Service account ID gets updated automatically based on the service account name, but can be changed if desired.
  • Click on Continue.
  • The service account does not require permissions on project level, therefore do not select a role.
  • Click on Continue.
  • Only grant other users access to this service account if absolutely necessary, which is typically not the case.
  • Click on Create Key in the Keys section.
  • Select the JSON as key type and click on Create.
  • The JSON file will be downloaded automatically. Save the JSON file (e.g. MailStore API Access-e035d2ad4f35.json) in a secure location as it allows access to cloud resources of your organization.
  • Click on Close and then on Done to finish the creation of credentials.

Perform Domain-Wide Delegation of Authority

To grant the service account domain-wide access to your G Suite account, so called domain-wide delegation must be enabled as described in these steps:

  • Click on the newly created service account to access its details.
  • Click on Show Domain-wide Delegation.
  • Check the Enable G Suite Domain-wide Delegation box.
  • Click on Save.

As a result, a new OAuth 2.0 Client was created for the service account that has been created in the previous step.

Creating OAuth 2.0 Client for User Authentication

To allow users to log into MailStore by authenticating with Google, another OAuth 2.0 Client must be created that is suitable for OpenID Connect.

  • Click on Credentials' in the left navigation pane.
  • Click + Create Credentials and select OAuth client ID from the drop-down list.
  • Select Web application as Application type.
  • Enter a Name, e.g. MailStore Server OpenID Connect.
  • In the Authorized redirect URIs section, click on + Add URI.
  • Enter the URI that is reachable by clients in the URIs field in the following scheme:

Granting Access on G Suite Account to Project

Once created, grant the newly created project fine-grained access to your G Suite account by defining the Google APIs it is allowed to use.

  • Open the Google Admin console and log in with a G Suite domain admin.
  • Select Security > API controls from the menu.
  • Unter Domain wide delegation, click Manage domain wide delegation.
  • On the Domain-wide delegation page, click Add new.
  • Enter the Client ID of the OAuth 2.0 Client that is linked with the service account.
  • Under OAuth Scope, add the following scopes:,,
  • Click Authorize.

Accessing Directory Service Integration

  • Log on to MailStore Client as a MailStore Server administrator.
  • Click on Administrative Tools > Users and Archives > Directory Services.
  • In the Integration section, change the directory service type to G Suite.
Gapps sync 01.png

Connection to G Suite

For synchronization MailStore Server requires information on how to connect to the G Suite.

  • Key ID
    To import the private key, select the JSON file (e.g. MailStore API Access-e035d2ad4f35.json) that has been generated by Google for the service account.
  • Service Account
    The service account is determined automatically from the JSON file.
  • User Name
    The email address of a G Suite Administrator (e.g.

User Database Synchronization

After configuring the connection settings as described above, you can specify filter criteria for the G Suite synchronization in this section.

  • Sync only these groups
    Choose one or several G Suite groups if you only want their members to be created as MailStore Server users. That way it's possible to exclude certain users from being synchronized to MailStore Server.


  • Automatically delete users in MailStore Server
    Here you can choose whether users that have been deleted in the G Suite Account will also be deleted in the MailStore user database by the synchronization. If the archive folder of such a user already contains archived emails, only the user entry but not its archive folder will be deleted in MailStore. Additionally, only MailStore users that have their authentication method set to Directory Services will be deleted.

Assigning Default Privileges

By default, users that have been synchronized to MailStore Server from G Suite Account have the privilege to log on to MailStore Server as well as read access to their own user archive.
You can configure those default privileges before synchronization, for example, to assign the privilege Archive E-mail to all new users. To do this, click on Default Privileges...
More information on managing user privileges and their effects is available in the chapter Users, Folders and Settings which also has details on editing existing privileges.

Running Directory Services Synchronization

Click on Test Settings to check synchronization configuration and the results returned by the G Suite Account without any changes to the MailStore Server user database being actually committed.

To finally run the synchronization, click on Synchronize now. The results are shown with any changes committed to the MailStore Server user database.

ApplicationIntegration sync 02.png

You can test the authentication for a user by first selecting him from the list and then clicking on the button on the lower left. You will now be asked for that user's password. Upon clicking OK you'll receive a message whether the authentication has been successful.

Important Notice: For authentication with G Suite to work, the setting Allow less secure apps of the respective G Suite user has to turned on if it has not been enforced for all users (see above).

Login with G Suite Account Credentials

After synchronization MailStore users can log on to MailStore Server with their G Suite Account username and G Suite Account password.

About MailStore

  • MailStore Server is one of the leading email archiving solutions for SMB.
  • For private use there is a free tool for email archiving furthermore: MailStore Home.