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 to suit your business or organization.

These are some examples of different ways you can route and store email:

  • Gmail scans inbound mail for spam and compliance purposes, but the mail is stored on your external mail server.

  • Some users get their messages in Gmail inboxes, and other users get their messages from your local server.

  • All users get their messages in Gmail, but messages for unknown users are routed to a special mailbox or server.

  • All messages sent to a specified user automatically copy (Cc:) another user.

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, use these compliance settings:

The Non-Gmail mailbox setting can be used to filter spam and route all non-spam messages to your external mail server. The non-Gmail mailbox setting has more features than routing rules.

Users can log in to a Message Center or receive regular reports that list their spam messages. Users decide which of these messages they consider safe and want sent to their non-Gmail mailbox.  These users don't have access to Gmail. They get their messages from a local mail server.

Note: Starting October 2019, Message Center and Quarantine Summary will be deprecated. Learn more in Manage Spam Messages. We recommend using the methods described in Manage Spam Messages to manage spam when Message Center is no longer available.

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

Learn more about Setting up routing for your domain or organization.

Before you begin

Before you set up any routing and delivery settings, create a list of mail hosts, also called routes. Add these routes in the Google Admin console.

Route incoming email

You can route incoming messages with different delivery methods.

If your organization is using Gmail only, use direct delivery (default configuration). Incoming messages addressed to G Suite users are delivered to the recipient's Gmail inbox. Messages addressed to users who aren't  G Suite users in your domain, are removed. You can optionally set up a catch-all address for these misaddressed messages.

If your organization uses an external mail server for storage and message delivery, such as a Microsoft® Exchange server, Gmail processes the incoming messages first. Gmail filters for spam and other problem messages, then routes messages to the external server.

Split delivery routes messages to either the Gmail server or an external server.

Dual delivery routes messages to both the Gmail server and an external server.

You can also route incoming messages to:

  • A catch-all address
  • Additional recipients
  • A non-Gmail mailbox

Route messages with split delivery

Use split delivery to deliver incoming messages to either a Gmail inbox or to a legacy system inbox, depending on the recipient. 

We recommend this method if:

  • Some of your users use Gmail, and others use a different mail system. For example, you might need to store messages sent to the Legal department on your legacy server.
  • You're migrating to Gmail from a legacy mail server. Use this method to test Gmail with a subset of users. During the testing, the MX records for your domain point to Gmail. Users who have been added in the Admin console will receive messages in their Gmail inboxes. Set up a catch-all routing rule for unregistered users who need to get messages from the legacy mail server. 

To set up split delivery:

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

  2. Do the initial steps to Sign in with Google, 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 their email address. 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. Select Show options and change the Account types to affect setting to Unrecognized/Catch-all.

  8. Save the configuration.

Route messages with dual delivery

Set up dual delivery when you need to deliver messages to 2 or more inboxes. For example, users can receive messages in a Gmail inbox and a non-Gmail inbox (Microsoft Exchange or an archiving server).

Get detailed steps for setting up mail dual delivery.

Set up a catch-all address

A catch-all address ensures that messages sent to an incorrect email address for a domain are still received.

To set up a catch-all address:

  1. Do the initial steps to sign 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

Use multiple routing settings to automatically forward messages to other recipients. You can then create separate policies for each user.

To route messages to additional recipients:

  1. Do the initial steps to sign 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. Specify a single recipient 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, use the Non-Gmail mailbox setting to:

  • Route non-spam messages to an external server 
  • Hold spam in a message center or quarantine report

Users can determine if the messages aren't spam and should be routed to the external server.

Route outbound mail

Send all mail through a gateway server

To route outbound messages, set up an outbound gateway server. The gateway server usually processes the outbound messages in some way before delivering them.

Learn more in Set up an outbound gateway.

Set up 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.

Use the SMTP relay service setting to filter messages for spam and viruses before they reach external recipients. This setting also lets you apply G Suite mail security settings to outgoing messages.

Learn more about setting up  the SMTP relay service.

Compliance routing

Content compliance and objectionable content

You might want certain types of messages handled in a specific way. For example, you might want to route messages with specific content to your legal department.

Define a new primary destination (the default destination is Gmail) or create 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

To define a new primary destination (the default destination is Gmail) or add additional destinations for messages that match a specific attachment type, use the Attachment compliance setting. For example, 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 (TLS) when users correspond with specified domains and email addresses.

Set up 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 is rejected and outbound mail is not transmitted.

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

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 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 is unsuccessful

If a message is routed from a Gmail or G Suite server to an external recipient server and the connection isn't made because of a timeout, refusal, or 400-series error, the message is held and tried again. Gmail tries to send the message every few minutes, for up to 7 days. After 7 days, the message is returned to sender.

If you add a new server while Gmail is trying to reend the message, the message is routed to the original server, not the new one.

If there’s a 500 series error for the message, the message is rejected immediately.

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