Set options for non-Gmail mailbox users

If your organization uses a non-Gmail mail server, such as Microsoft Exchange or other non-Google Simple Mail Transfer Protocol (SMTP) service, you can use the Non-Gmail mailbox setting to reroute messages to your users’ non-Gmail mailboxes.

You can also use the Non-Gmail mailbox setting to allow non-Gmail users to sign in to Message Center, and to configure quarantine summary reports for your non-Gmail users. Both Message Center and quarantine summary are only for non-Gmail users, and these features allow your non-Gmail users to manage spam.

After you configure an advanced Gmail setting, it may take up to one hour for that configuration to propagate to individual user accounts. You can track prior changes under Admin console audit log

WARNING: Enabling this setting will cause all mail for affected users to be deleted if it is older than 30 days. (Mail is retained for 30 days to support Quarantine Summary and Message Center functionality for Non-Gmail mailbox users).

Use the Non-Gmail mailbox setting only for users whose mailboxes are located on an on-premise/non-Gmail mail server. You should never enable the Non-Gmail mailbox setting for users that use Gmail as their email service, as they will lose all access to Gmail and most of their mail will be deleted. Use this setting to allow the use of Gmail's spam filtering (and other G Suite features such as content compliance and mail routing) for non-Gmail mailbox users.

Message Center

Message Center is a web-based console that, by default, lets users view and manage messages quarantined as spam. In addition, you can choose to enable Message Center to include a list of messages that were delivered to a user's non-Gmail Inbox.

To access Message Center, users must sign in at using their G Suite account username and password. Let your users know that they will need their G Suite passwords. If a user doesn't have or can't remember the password, you can reset that user's password.

From within Message Center, a user can scan for any messages falsely identified as spam and mark them as safe for delivery. This trains the system not to identify similar messages as spam, and the indicated messages are then delivered to the user's non-Gmail Inbox.

In addition, we recommend that you check the Allow users to report spam box, which enables users to scan a list of delivered messages and mark any as spam. This trains the system to identify similar messages as spam in the future.

Note: Messages are removed from Message Center after 30 days. Messages that were in the Delivered folder will still be available in the user's non-Gmail Inbox, because they were delivered there.

Users can also delete any messages displayed in Message Center, create whitelists of approved contacts, and customize sign-in and display settings. For more details about the user experience with Message Center, see  Manage messages in Message Center.

If you enable user access to Message Center, we recommend that you send your users a notification email (here is a sample you can use) about their access. G Suite does not automatically send a Message Center access notification email.
Quarantine summary reports

The quarantine summary is a periodic digest sent to a user’s inbox. By default, it contains a list of emails that were recently marked as spam. Users can quickly scan this list for falsely quarantined messages, and mark these messages as Not spam. This trains the system not to identify similar messages as spam, and the indicated messages are then delivered to the user’s non-Gmail inbox.

In addition, we recommend that you check the Allow users to report spam box. If you select this option, the summary reports will also include emails that the system did not mark as spam. Users can scan this list for messages that should have been quarantined, and report these messages as spam. This trains the system to identify similar messages as spam in the future.

Note: If a user later decides to change a given message’s status from not spam to spam or vice versa, this change can be done from the quarantine summary.

A quarantine summary report looks like this:

Quarantine summary report

If no spam messages were quarantined during the time period that you set up, users will receive quarantine summaries indicating that no spam was received. (Users who receive no mail at all during the period may not receive an empty summary.)

Note: If a user wants to change a message's status, the user must do so within 30 days of receiving the original message—not the summary. If a user clicks a Deliver or Report spam link after the message has expired from Gmail, an error message appears. 

For more details about the user experience with quarantine summary, see Quarantine summary report.

Configure the Non-Gmail mailbox setting

Similar to other email security settings in the Google Admin console, the Non-Gmail mailbox setting applies to all users in an organizational unit (OU). Users within child OUs inherit the setting configurations you create for the parent OU.

If you enable this setting, you can't route the primary mail stream to a Gmail mailbox. G Suite does not support the use of both a Gmail mailbox and another, separate non-Gmail mailbox. You must choose one (Gmail or a non-Gmail mailbox) for your users.

  1. Sign in to the Google Admin console.
  2. From the Home page, go to Apps > G Suite > Gmail > Advanced settings.
  3. In the Organizations section, highlight your domain or the organizational unit for which you want to configure this setting (see Configure advanced settings for Gmail for more details).
  4. Scroll to the Non-Gmail mailbox section, or enter this term in the Search settings field:
    • If the setting's status is Not configured yet, click Configure. The Add setting dialog box appears.
    • If the setting's status is Locally applied, click Edit to edit an existing configuration. The Edit setting dialog box appears.
    • Click Add another to add a new configuration. The Add setting dialog box appears. You can do this for either inherited or locally applied settings.
  5. In the field at the top of the dialog box, enter a short description for this configuration; for example, Eng Non-Gmail Mailbox Settings.
  6. In the Mail server section, select a mail host from the drop-down list.
    Note: If you have not yet set up your receiving mail routes, you’ll need to do this now. (For instructions, see Add mail routes with the Hosts tab. For more details about mail routing, including use cases and examples, see Manage mail routing and delivery: Guidelines and best practices.)
  7. To let users access Message Center, check the Allow users to log in to Message Center box.
  8. To turn on quarantine summaries for your users, check the Enable periodic summaries box and do the following:
    • Select an approximate delivery time (based on the time zone configured for your domains in the Google Admin console).
    • Select the days of the week. For example, highlight all seven boxes so that your users can receive the quarantine summary everyday, or check just one box for weekly delivery.
  9. To include clean mail messages—that is, messages delivered to a user's Inbox—in Message Center and the message summary, check the Allow users to report spam (recommended) box. This box is checked by default if you enable periodic summaries.
  10. When you're finished making changes, click Add setting or Save to close the dialog box.

    Any settings you add are highlighted on the Advanced settings page.
  11. Click Save changes at the bottom of the Advanced settings page.
Note: Quarantine summary reports are sent with a From address of The envelope sender is the same as the message recipient. You can use Email log search to search for a quarantine summary report by searching for the recipient of the report and putting that recipient address as the sender address.
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