Set up mail dual delivery

Send messages to two or more inboxes

If you need to send your organization's mail messages to two or more inboxes, set up dual delivery. With dual delivery, messages are delivered to a Gmail inbox and to a non-Gmail inbox. Examples of non-Gmail inboxes include Microsoft Exchange and archiving servers.

Learn more about other email routing and delivery options.

How dual delivery works

With dual delivery, incoming mail is delivered to a primary mail server first. The primary server delivers each message to the inboxes associated with it, then forwards all messages to a secondary mail server. The secondary server delivers the messages to the secondary server inboxes.

The primary server is the mail server identified in the MX records for your public domain.

Note: The primary server can be either Gmail or your legacy mail server, however we recommend you use Gmail. Use your legacy server as the primary server during migration to Gmail. When migration is done, update your mail to deliver only to Gmail.

Gmail as primary server

Use basic routing settings to set Gmail as the primary server for dual delivery. Learn more about how to Set up routing for your domain or organization.

Set up dual delivery with Gmail as the primary server:

  1. If you haven’t yet, add the route for the legacy server.
  2. Do the initial steps to sign 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 Arrow and select Advanced.
  8. Select Change route.
  9. From the list, select the secondary mail route.
  10. Scroll down and click Save.
  11. Configure more parameters as needed.
  12. Save the configuration.
  13. Configure the Inbound gateway setting.

Legacy server as primary server

We recommend using Gmail as the primary server for dual delivery. If you must use your legacy server as primary, for example during migration, use one of these methods:

  • Set up server-based forwarding from your legacy server to Google. This is the preferred method.
  • If your legacy server doesn’t support server-based forwarding, set up forwarding to Google test domain aliases.

If you use your legacy server as primary, don't update your MX records to Google.

Server-based forwarding

Set up server-based message forwarding on your legacy server:

  1. Sign in to your domain account and confirm that your MX records refer to your legacy mail server.
  2. Set up rules on the legacy server to forward all mail to ASPMX.L.GOOGLE.COM.

    For instructions on how to set up server-based forwarding, refer to the documentation for your legacy mail server.

  3. Add the legacy mail server as an inbound mail gateway to:
    • Set up Gmail to get a high volume of mail from the legacy server.
    • Improve SPF check accuracy. Mail coming from an inbound gateway is treated as an internal message. SPF checks are made against the server that sent the message to your legacy server.
  4. Send a test message to each user's legacy server email address.

    Confirm that users get the test message in both their legacy server inbox and their regular Gmail inbox.

Forwarding to test domain aliases

When you set up mail forwarding with test domain aliases, the legacy server forwards incoming mail to each user's domain alias. The domain alias then delivers the messages to each user's regular Gmail account.

Set up forwarding to domain aliases:

  1. Set up mail forwarding on your legacy server. Messages sent to legacy server addresses are forwarded to the corresponding domain alias.

    For instructions on how to forward mail and how to set up forwarding rules, refer to the documentation for your legacy mail server. Generally, you set up forwarding rules on a user-by-user basis.

  2. Add the legacy mail server as an inbound mail gateway to:
    • Set up Gmail to get a high volume of mail from the legacy server.
    • Improve SPF check accuracy. Mail coming from an inbound gateway is treated as an internal message. SPF checks are made against the server that sent the message to your legacy server.
  3. Send a test message to each user's legacy server email address.

    Confirm that users get the test message in both their legacy server inbox and their regular Gmail inbox.

About test domain aliases

Your G Suite account comes with a test domain alias, and each user is automatically assigned a test domain email address:

  • Test domain alias format: domain-name.test-google-a.com
  • Test domain email format: username@domain-name.test-google-a.com

For example, if your domain is solarmora.com, your test domain aliases are:

  • Test domain alias: solarmora.com.test-google-a.com
  • Test domain email: janedoe@solarmora.com.test-google-a.com

Learn more about test email addresses.

Secondary domain alias emails

Only your primary domain is assigned a domain alias and corresponding email addresses. If your users' email addresses are not part of the primary domain, create a secondary domain.

Update the MX records for the secondary domain to point to Google.

Learn more about domain aliases.

Was this article helpful?
How can we improve it?