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    Email routing and delivery

    As a G Suite administrator, you control how email for your organization is routed and stored. You can custom-fit routing and delivery suit to your business or organization.

    For example, you may want:

    • Gmail to scan your inbound mail for spam and compliance purposes, but store the mail on your external mail server.

    • Some users to receive mail in Gmail inboxes, and others to access mail from your local server.

    • All users to use Gmail exclusively, but route messages for unknown users to a special mailbox or to an external server.

    • Messages for a specific user to Cc: another recipient.

    You use the Routing setting to configure inbound, outbound, and internal delivery options, such as dual delivery and split delivery.

    If you have a more specific need, like routing certain messages based on content, you can use the compliance settings including Content compliance,  Attachment complianceObjectionable content, or TLS compliance.

    Finally, there's the Non-Gmail mailbox setting which can be used to filter for spam and reroute all non-spam messages to your external mail server. This setup can also be accomplished using a Routing rule, but the Non-Gmail mailbox setting comes with extra features. Users can log in to a Message Center or receive regular updates listing their spam messages and decide which of these messages they consider safe and want routed to their non-Gmail mailbox. With this setting, users exclusively access their clean mail with their on-premise mailbox and have no access to a Gmail mailbox.

    All of these settings can be tailored for different people and teams using organizational units.

    Before you begin

    Before setting up any routing and delivery settings, create a list of mail hosts, also called routes. Then, you need to add the routes in the Google Admin console.

    Route incoming email

    You can route incoming messages using different delivery methods.

    If your organization is exclusively using Gmail, you can use direct delivery, which is the default configuration. Incoming messages addressed to G Suite users are delivered to the Gmail inbox of the recipient. If a message is addressed to a user who isn't a G Suite user in your domain, the mail server discards the message unless a catch-all address has been configured to receive misaddressed messages.

    If your organization uses an external mail server for storage and message delivery, such as a Microsoft® Exchange server, incoming messages are first processed by the Gmail server, such as filtering for spam, and then routed to the external server. You use the split delivery method to route the messages to either the Gmail server or an external server. You use the dual delivery method to route the messages to both the Gmail server and an external server. 

    You can also route incoming messages to a catch-all address, to additional recipients, and to a non-Gmail mailbox. 

    Route messages using split delivery

    With split delivery, an incoming message is delivered to either a Gmail inbox or a legacy system inbox, depending on the recipient. 

    This method works well if some of your users use Gmail, and others use a different mail system. For example, you might need to implement special handling for certain types of email, such as messages to the Legal department.

    This method also works well if you are migrating to Gmail from a legacy mail server, and you want to run a test with a subset of users. During the test period, the MX records for your domain point to Gmail and those users who’ve been added in the Admin console will receive messages in their Gmail inboxes. For unregistered users to continue receiving messages via the legacy mail server, you can set up a catch-all routing rule. 

    The following procedure describes the basic steps for setting up split delivery using the Routing setting. For details about all of the Routing setting controls, see Set up routing for your domain or organization.

    To set up split delivery:

    1. If you haven’t yet, add the route for the external server.

    2. Do the initial steps to log in, select the organization if necessary, open the Routing setting, and enter a description for the new setting.

    3. For email messages to affect, select Inbound, or Internal-receiving, or both.

    4. Set up an envelope filter if you want the rule to affect only specific envelope senders and recipients. You can specify single recipients by entering an email address for that user. You can also specify groups.

    5. Under For the above types of messages, select Modify message and configure the settings for your scenario.

    6. Select Change Route, select the external server from the list, then scroll down and click Save.

    7. Configure additional parameters as needed.

    8. Save the configuration.

    Route messages using dual delivery

    You set up dual delivery to deliver email messages to 2 or more inboxes. For example, users can receive messages in a Gmail inbox and a non-Gmail inbox, such as a Microsoft Exchange inbox or an archiving server.

    With this configuration, incoming mail is delivered to a primary mail server, which processes and delivers each message. The primary server then forwards a copy of the message to a secondary mail server, which delivers it to the second inbox. The primary server is the mail server identified in the MX records for your public domain.

    If the external server is the primary server, you configure that server to also forward messages to Google. You also configure the Inbound gateway setting in so that Gmail knows that the incoming mail is being rerouted to it from the external server and performs the appropriate SPF checks.

    If Gmail is the primary server and you want the external server to also receive copies of message, you set up dual delivery using the Routing setting. 

    The following procedure describes the basic steps for setting up dual delivery using the Routing setting. For details about all of the Routing setting controls, see Set up routing for your domain or organization.

    To set up dual delivery:

    1. If you haven’t yet, add the route for the external server.
    2. Do the initial steps to log in, select the organization if necessary, open the Routing setting, and enter a description for the new setting.

    3. For email messages to affect, select Inbound, or Internal-receiving, or both.

    4. Set up an envelope filter if you want the rule to affect only specific envelope senders and recipients. You can specify single recipients by entering an email address for that user. You can also specify groups.

    5. Under For the above types of messages, select Modify message.

    6. Under Also deliver to, select Add more recipients then click Add to add the secondary mail route.

    7. Under Recipients, click the Down arrow Down Arrowand select Advanced.

    8. Select Change route.

    9. Select the secondary mail route from the list.

    10. Scroll down and click Save.

    11. Configure additional parameters as needed.

    12. Save the configuration.

    Set up a catch-all address

    You can create a catch-all address to ensure that messages that are accidentally addressed to an incorrect email address for a domain can still be received.

    The following procedure describes the basic steps for setting up a catch-all address using the Routing setting. For details about all of the Routing setting controls, see Set up routing for your domain or organization.

    To set up a catch-all address:

    1. Do the initial steps to log in, select the organization if necessary, open the Routing setting, and enter a description for the new setting.

    2. For email messages to affect, select Inbound, Internal-receiving, or both.

    3. Set up an envelope filter if you want the rule to affect only specific envelope senders and recipients. You can specify single recipients by entering an email address for that user. You can also specify groups.

    4. Under For the above types of messages, select Modify message.

    5. Under Envelope recipient, select Change envelope recipient.

    6. Select Enter new username.

    7. Enter a catch-all address in the empty field next to @exisiting-domain. For example, enter jsmith.

    8. Click Show options.

    9. Under Account types to affect, check the Unrecognized / Catch-all box. Uncheck Users and Groups.

    10. Click Add setting.

    11. Save the configuration.

    Route messages to additional recipients

    You can set up multiple routing settings to forward messages to additional recipients. You can then create separate policies for each user.

    The following procedure describes the basic steps for routing messages to additional recipients using the Routing setting. For details about all of the Routing setting controls, see Set up routing for your domain or organization.

    To route messages to additional recipients:

    1. Do the initial steps to log in, select the organization if necessary, open the Routing setting, and enter a description for the new setting.

    2. For email messages to affect, select Inbound, or Internal-receiving, or both.

    3. Set up an envelope filter if you want the rule to affect only specific envelope senders and recipients. You can specify single recipients by entering an email address for that user. You can also specify groups.

    4. Under For the above types of messages, select Modify message.

    5. Under Also deliver to, check the Add more recipients box.

    6. Click Add.

    7. Under Recipients, make sure that Basic is selected in the list. 

    8. Enter the recipient’s email address and click Save.

    9. Click Add Setting or Save. New settings are added to the Advanced settings page.

    10. Save the configuration.

    Set up non-Gmail mailbox delivery

    If your organization uses an external mail server, you can use the Non-Gmail mailbox setting to route non-spam messages to an external server and hold spam in a message center or quarantine report. Then, users can decide if the messages aren’t spam and should be routed to the external server.

    Route outbound mail

    Send all mail through a gateway server

    You can set up an outbound gateway server to route outbound messages. The gateway server typically processes the outbound messages in some way before delivering them.  For details, see Set up an outbound gateway.

    Configure SMTP relay service to route mail through the Gmail server

    If your organization uses non-Gmail email server software, such as Microsoft® Exchange or another non-Google SMTP service, you can configure the SMTP relay service to route outgoing mail through the Gmail server. You use the SMTP relay service setting to filter messages for spam and viruses before they reach external contacts. The setting also allows you to apply G Suite email security settings to outgoing messages. Learn more about setting up  the SMTP relay service.

    Compliance routing

    Content compliance and objectionable content

    You can use content-compliance routing to implement special handling for certain types of email, such as to route messages with specific content to your legal department. Do this by defining a new primary destination (by default, the Gmail server) or by creating additional destinations that match specific text strings or patterns. For example, you can set up a content match on a word, such as "confidential," and then change the primary destination to a server that supports encryption.

    Learn about content compliance and objectionable content.

    Attachment compliance

    You can define a new primary destination (by default, the Gmail server) or add additional destinations for messages that match a specific attachment type using the Attachment compliance setting. For example, you can set up a secondary destination that delivers any message with image attachments to the Human Resources team.

    Learn about attachment compliance.

    Require a secure connection before routing mail

    You can require mail to be transmitted via a secure connection (using TLS) when users correspond with specific domains and email addresses. You can configure the Secure transport (TLS) compliance setting by organizational unit for inbound and outbound mail. If TLS is unavailable at a domain that you specify, inbound mail will be rejected and outbound mail will not be transmitted.

    Note: If you set up an outbound gateway server that uses TLS, outbound messages on the enforced TLS list that are sent to domains that don’t support TLS will not be rejected.

    Learn about secure transport (TLS) compliance.

    Troubleshoot

    When routes conflict

    You can set up a domain-wide routing policy for incoming messages. You can also define delivery routes based on a message’s content or attachments. Learn about which routing setting take precedence.

    If there’s a conflict with legacy routing controls, any routing settings described here will override any legacy settings. Learn more about legacy routing controls.

    If message routing or delivery fails

    If a message is routed from a Gmail or G Suite server to an external recipient server and the connection can’t be made due to a time-out, refusal, or 400-series error, the message will be held and retried. A retry attempt is made every few minutes.

    If you update your settings with a new host while a message is still being retried, the message will still be routed to the original server, not the updated one.

    Messages are held and retried for up to 7 days before they’re returned to the sender. If there’s a permanent failure (500-series error), the message is immediately rejected.

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