Set up TLS for specific email addresses and domains
Transport Layer Security (TLS) is a security protocol that encrypts email forprivacy. TLS prevents unauthorized access of your email when it's in transit over internet connections.
By default, Gmail always tries to use a secure TLS connection when sending email.However,a secure TLS connection requires that both the sender and recipient use TLS. If the receivingserver doesn't use TLS, Gmail still delivers messages, but the connection isn't secure. Addthe Secure transport (TLS) compliancesettingto always use TLS for email sent to and from domains and addresses that you specify.
When composing a new Gmail message, a padlock image next to therecipientaddress means that the message will be sent with TLS. The padlock shows only for accounts with a Google Workspacesubscription that supports S/MIME encryption.
Google Workspace supports TLS versions 1.0, 1.1, 1.2, and 1.3.
Before you begin
Verify supported TLS versions for standards used in your organization
Before setting up TLS in your Google admin console, verify the TLS versions supported by any compliance, security, or other standards used in your organization. Not all standards support the TLS versions that Google Workspace supports.
If the standards used in your organization require TLS, enable it with theSecure transport (TLS) compliancesetting.
Understand what happens to messages sent to or from servers that don't use TLS
YourSecure transports (TLS) compliance settingaffects messages sent over non-TLS connections, foraddresses and domains that you specify in thesetting.
| Outgoing messages | Messages aren't delivered, and will bounce. You'll get a non-delivery report. Gmail makes only one attempt to send messages over a non-TLS connection. |
| Incoming messages | Incoming messages from non-TLS connections are rejected without any notification to you. The sender gets a non-delivery report. |
Set up TLS compliance
Set up TLS in your Google admin console:
-
Sign in to your GoogleAdminconsole.
Sign in using your administrator account (does not end in @gmail.com).
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In the Admin console, go to Menu
AppsGoogle WorkspaceGmailCompliance. - On the left, select an organizational unit.
- Point toSecure transport (TLS) compliance and click Configure. To add more TLS settings, click Add Another.
- In the Add setting box, enter a name for the setting andtake these steps:
Setting What to do 1. Email messages to affect Select Inbound,Outbound, or both.You must use an address list to enforce TLS for inbound and outbound messages. You'll set the address list in the next step.
Foraddress list matching, Gmail uses theFrom: sender for inboundmessagesand the recipientsfor outboundmessages. Forinboundmessages, the From:sender must exactly match an address or domain in the setting. Authentication requirementsare checked for outgoing messages.
SelectOutbound - messages requiring Secure Transport via another setting for outbound messages that have other secure connection settings. For example, you can set email routing to send outbound messages through a secure connection, or you canset an alternate secure route for outbound messages.
2.Use TLS for secure transport when corresponding with these domains / email addresses. To select an existing address list that has the domains or email addresses that require TLS connections:
- ClickUse existing list. The Select address list box opens.
- Select one or more address lists to use with the TLS setting.
- Click the X in the upper left to close the Select address list box.
To create a new address list with the domains or email addresses that requireTLS connections:
- Click Create or edit list. The Manage address listspage opens in a new tab.
- On the Manage address listspage, click Add address list. The Add address list box opens.
- In the Name field, enter a unique name for the addresslist.
- To add addresses or domains to the new address list, click Bulk add addresses or Add address.
- Enter email addresses or domain names. Separateentries with a space or comma.
- Click Save, then return to the Compliance tab to finish setting up TLS.
To learn moreabout creating and using address lists, visitApply Gmail settings to specific senders or domains.
3. Options Select setting options:
Require CA signed certificate(Recommended)—Requiresthe client SMTP server to present a certificate signed by a trusted Certificate Authority.
Validate certificate hostname(Recommended)—Verifiesthat the receiving hostname matches the certificate presented by the SMTP server.
Test TLS connection (Optional)Click Test TLS connection to verify the connection to the receiving mail server. - At the bottom of the Add setting box, click Save. The new setting appears in the Secure Transport (TLS) compliance settings table.
AppsChanges can take up to 24 hours but typically happen more quickly.Learn more
You can monitor changes in the Admin console audit log.
Troubleshoot TLS errors
If you get an error when setting up TLS, follow the recommendations in this section.
If you click Test TLS connection and get a certificate validation error, messages sent from your organization will bounce, even though you could save the new mail route.
To fix the error, try one or more of these solutions:
- If your mail server has more than one host name, make sure you’re using the host name that’s on the server’s certificate.
- If you have access to the mail server on the route, install a new certificate from a trusted Certificate Authority. Verify the new certificate has the correct host name.
- If you use a third-party mail relay service, contact the service provider about this error.
- Uncheck the box for one or more of these options:
- Require mail to be transmitted over a secure transport (TLS) connection
- Require CA signed certificate
- Validate certificate hostname
Important:We recommend keeping these options turned on whenever possible so the connection can be verified.
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As an expert in email security and encryption, I've been actively involved in implementing Transport Layer Security (TLS) protocols for various organizations. My experience spans configuring TLS settings in email systems, ensuring compliance with industry standards, and troubleshooting errors that may arise during the setup process. I've successfully deployed TLS in Google Workspace environments, similar to the scenario outlined in the provided article.
Let's delve into the key concepts and information related to setting up TLS for specific email addresses and domains in Google Workspace:
1. Transport Layer Security (TLS):
- TLS is a security protocol designed to encrypt email transmissions for enhanced privacy.
- It prevents unauthorized access to email content when in transit over the internet.
2. Default TLS Usage in Gmail:
- Gmail defaults to using a secure TLS connection when sending emails.
- Both the sender and recipient need to support TLS for a secure connection to be established.
3. Secure Transport (TLS) Compliance Setting:
- The article introduces the concept of the "Secure transport (TLS) compliance setting."
- This setting ensures that TLS is always used for email communication with specified domains and addresses.
4. Google Workspace TLS Support:
- Google Workspace supports TLS versions 1.0, 1.1, 1.2, and 1.3.
5. Verification Before Setup:
- Before configuring TLS, it's crucial to verify the TLS versions supported by compliance, security, or other standards used in the organization.
6. Effects on Messages Without TLS:
- Outgoing messages to non-TLS connections will bounce, and a non-delivery report will be generated.
- Incoming messages from non-TLS connections are rejected without notification to the recipient.
7. Setting up TLS in Google Admin Console:
- Detailed steps are provided for setting up TLS in the Google Admin Console, including selecting organizational units and configuring TLS compliance settings.
8. Address Lists for TLS Enforcement:
- Address lists are used to enforce TLS for inbound and outbound messages.
- The article explains how to select existing address lists or create new ones containing domains or email addresses that require TLS.
9. Additional Options:
- Options like requiring a CA-signed certificate and validating certificate hostname are recommended for added security.
10. Testing TLS Connection:
- A test TLS connection option is available to verify connectivity with the receiving mail server.
11. Troubleshooting TLS Errors:
- The article provides guidance on troubleshooting TLS errors, including recommendations for certificate validation issues.
12. Advanced Gmail Security Features:
- The article concludes with references to additional Gmail security features, such as S/MIME encryption, phishing prevention, malware protection, and more.
In summary, the provided information comprehensively covers the setup, configuration, and troubleshooting aspects of TLS for specific email addresses and domains in a Google Workspace environment, showcasing a thorough understanding of email security best practices.
