Setting Up an Office 365 SMTP Relay with TLS ConnectorsSimple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails. An SMTP server is responsible for sending outgoing emails. Sometimes the functionality of a single SMTP server may be not enough, and you may need to configure an SMTP relay. What are SMTP relays? An SMTP relay is a service for transferring emails from one mail server to another. Show
In general, if you use Office 365, you don’t need to configure an SMTP relay to send email messages. An SMTP relay is used when you need a higher level of anti-spam and antivirus protection for incoming emails compared to your on-premises email server, but you cannot move to Microsoft email servers only. You may need to keep the on-premises email server for several reasons, including for internal company communication without an internet connection, for higher storage limits for users’ mailboxes, or the number of daily emails exceeds the Office 365 daily limit. Other use cases for SMTP relay include sending automated email messages from a device or developed application and improving email deliverability. You may need to use Office 365 SMTP relay if you are going to send a bulk email (for a marketing campaign, for example) and route email through a trusted third-party server that provides a high level of security. This blog post explains Office 365 SMTP relay and configuration basics. Before we start Office 365 is a suite of highly reliable web services. However, data residing in the cloud is still vulnerable to accidental deletions and ransomware attacks. To avoid permanent data loss in Microsoft 365, use third-party solutions like NAKIVO Backup for Office 365. Get the Free Trial now! Requirements for Setting Up SMTP RelayThe sending application (the on-premises email server) must support TLS, connect to the Office 365 servers on port 587 (the SMTP port for Office 365 with encryption enabled), and authenticate with Office 365. A valid certificate must be used. It is recommended that you use a certification authority-signed (CA-signed) certificate whose name includes the domain name matching the domain name used by your organization’s email server. The advantage of using certificates issued by trusted certificate authorities is the ability to authenticate the identity of the certificate’s owner. CA-signed certificates are automatically trusted by web browsers and other applications. When you purchase a CA-signed certificate, your domain is validated, and there’s proof that you control the domain. Additional requirements and limitations are:
Read also the blog post about Office 365 SMTP settings. What are Office 365 Connectors?An Office Connector is a collection of instructions used to customize how email flows to and from your Office 365 organization. You can set up connectors in Office 365 to route email between Office 365 and your own email servers in both directions. You can configure Office 365 connectors for the mail flow between Office 365 and your on-premises Exchange server. Using a Connector from Your Mail Server to Office 365Let’s configure an Office 365 connector for the SMTP relay from your email server to Office 365. Open the Exchange admin center. You can use this link https://login.microsoftonline.com/jsdisabled. Go to Mail flow > Connectors in the navigation pane to open Office 365 SMTP relay settings. In my example, the list is empty because no connectors have been created yet. If you have previously created connectors, they should appear on this page. Click + Add a connector on the Connectors page to add an SMTP connector. The Add a connector wizard opens. New Connector. Select Your organization’s email server under Connection from. Under Connection to, Office 365 is greyed out. This default option is selected automatically when you select the Your organization’s email server radio button. Hit Next at each step of the wizard to continue. Connector name. Enter the connector name, for example, Office 365 SMTP relay TLS. Enter a description for the SMTP connector, for instance: A connector from the on-premises email server to Office 365 Select what to do after the connector is saved:
Authenticating sent email. Choose how Office 365 should authenticate and accept an email sent from your server. There are two available options. I select the first option:
Enter the domain name used by your organization. If your organization uses multiple domain names, enter any of the domains. If you prefer to select the second option, you should define the IP address of the domain server in your organization. Review connector. Review the selected options for the new SMTP connector in Office 365 and click Create connector. The Office 365 SMTP connector is now created. Using a Connector from Office 365 to Your Mail ServerNow let’s look at how to configure an Office 365 SMTP relay with a connector for mail flow in the other direction (from Office 365). Open the Exchange admin center and go to Mail flow > Connectors in the navigation pane. Hit + Add a connector (similarly as explained in the previous section). A wizard opens, and the New Connector screen is displayed. Select Office 365 in the Connection from the section. Select Your organization’s email server under Connection to. Hit Next at each step to continue. Connector name. Enter an SMTP connector name and description. Name: Office 365 SMTP relay TLS 2 Description: A connector from Office 365 to the on-premises email server Select the options to be applied after the connector is saved:
Use of connector. Specify your usage of this Office 365 SMTP connector. There are three options:
I select the first option in this example. Routing. Specify the smart host to which Office 365 should deliver emails. You can enter a fully qualified domain name (FQDN) or IP address. After entering the name or address of a server, hit the + button to add the server. Security restrictions. Select the security options. Since we are creating an Office 365 SMTP relay with TLS connectors, we should define the encryption parameters. Select the checkbox:
Then select one of the two available options:
Validation email. Enter the email address of the account on your email server to validate the configuration of the Office 365 mail relay. You can enter multiple email addresses. After entering an email address hit the + button. Then click Validate. Review connector. There is nothing to configure at this step. Review your configuration of the Office 365 SMTP relay and hit Create Connector. Using PowerShellThe alternative to the Exchange admin center GUI for configuring Office 365 SMTP relay with Office 365 connectors is using PowerShell. First, connect to Exchange Online PowerShell. Run the commands to create a TLS connector to receive email: $splat = @{ Name = 'SMTP Relay Office 365 (TLS)' ConnectorType = 'OnPremises' SenderDomains = '*' RequireTLS = $true TlsSenderCertificateName = '*.your-domain.com' } New-InboundConnector @splat Where: Name is the connector name. ConnectorType is the type of connector. The supported values are OnPremises or Partner. SenderDomains – this is a list of allowed sender domains. Verified sender domains are valid. Use an * (asterisk) to allow all verified domains for your tenant when you configure Office 365 SMTP relay with this connector. If you need to define multiple domains directly, you can enter a list of domains, for example, 'domain0.net', 'domain1.net'. RequireTLS – defines that TLS transmission is required for all email messages received by this connector. TlsSenderCertificateName is a certificate name or subject used by a sender. ConclusionThis blog post covered the basics of using Office 365 SMTP relays with TLS connectors. You can configure Office 365 connectors in the Exchange admin center and PowerShell. Mail flow between your mail server and Office 365 servers can be configured with connectors and TLS encryption. If you use Office 365 email services, it is recommended that you back up your data stored in Office 365. NAKIVO Backup & Replication supports Office 365 backup with support for Exchange Online, OneDrive for Business, and SharePoint Online. The solution can also back up on-premises Exchange Server running on physical or virtual machines. Download Free Edition of NAKIVO Backup & Replication and try the product to back up your data. Does Office 365 allow SMTP relay?SMTP relay lets Microsoft 365 or Office 365 relay emails on your behalf by using a connector that's configured with your public IP address or a TLS certificate.
How do I configure an internal SMTP Relay server for Office 365?Configure the SMTP Relay. From Server Manager, select Tools > Internet Information Services (IIS) 6.0.. Expand the server under Internet Information Services.. Right-click SMTP Virtual Server, and select Properties.. Click the Advanced button under the General tab, then click Add.. Specify the IP address of the SMTP server.. How do I connect SMTP to Office 365?OFFICE 365 SMTP SETTINGS. Server Address: smtp.office365.com.. Username: Your Office 365 Address (e.g. [email protected]). Password: Your Office 365 Password.. Port Number: 587 (With TLS). Authentication: Required.. Sending Limits: 10,000 Emails a day.. What is the SMTP server for Microsoft Office 365?IMAP and SMTP with OAuth2 Server Settings. |