Enable Sender Based Routing in Exchange Server (on-premises) 2007/2010/2013/2016/2019 - Tutorial¶

Sender Based Routing in Exchange Server¶

Exchange Server doesn’t support “Sender Based Routing” natively, but you can use an Exchange Server plugin to enable this function.

How it works:

• Install "EA Sender Based Routing" on Exchange Server.
• Create a customized Send Connector on Exchange Server.
• Create a Routing Rule in Sender Based Routing Manager.

“Sender Based Routing Agent” checks if current email message matches the routing rule based on Sender, Sender Group, Recipient, Headers or Subject conditions:

• If current email message does not match the rule, skip it, the default Send Connector will handle this email message.
• If current email message matches the rule, it will re-route the email to Send Connector specified in the rule.

Sender Based Routing Plugin Installation¶

You can download EA Sender Based Routing for Exchange Server Installer and install it on your server.

Double click the installer file and the installation will be executed automatically. The installer requires Exchange Server 2007 SP1/2010/2013/2016/2019 to be installed. If no Exchange Server is detected in your operating system, Setup will be aborted.

After the installation is completed, click “Sender Based Routing Manager” from Windows Start menu -> All Programs -> “EA Sender Based Routing” to begin the setup.

Create a New Send Connector¶

For example, if you want to relay all emails from domain “mysenderdomain.com” using a specified Send Connector, you would create a new Send Connector from the Exchange Admin Center (https://yourserver/ecp) -> mail flow -> Send Connectors, and name it as mysenderdomain.com.sbr.

• Then select Next, select "MX record associated with recipient domain" or "Route mail through smart hosts" based on your environment. If you selected "Route mail through smart hosts", add your smart host to the hosts list.

  

Create a Sender Based Routing Rule¶

Now we need to create a rule in "Sender Based Routing Manager" to re-route the email to the Send Connector created in previous section.

Here is how “Sender Based Routing Rule” works:

Open “Sender Based Routing Manager” from Windows Start menu -> All Programs -> “EA Sender Based Routing”

• Click Routing Rules -> New;
• Input a meaningful description for this rule;
• Select "if the sender address matches the following pattern";
• Input *@mysenderdomain.com in Sender Address, sender address supports wildcard (* and ?);
• Input mysenderdomain.com.sbr in Address Space, this is the address space you have added in your Send Connector.
• You can also click Browse to select the Send Connector instead of inputting the address space directly.

Finally, click Save, after this rule is created, all emails from *@mysenderdomain.com will be relayed by “mysenderdomain.com.sbr” Send Connector.

Moreover, you can click Address Space to open the advanced options, and set the different connectors based on recipient address.

You can enable Full Debug Log in Sender Based Routing Manager -> Journal, then send a test email from *@mysenderdomain.com, and check the log content to see if the rule works as expected.

Envelope Sender and From Address¶

An email has two addresses associated with sending it: the envelope sender, and the From address. The envelope sender is where computers should respond (in the case of bounce messages or errors); the From address is where people should respond.

In most cases, the envelope sender and the From address are identical. But they aren’t same always. For example, a non-delivery report always uses null address (<>) as the envelope sender address, and use the postmaster address as the From address.

In SBR 1.1.0.6 or earlier version, the envelope sender is used to match the sender pattern; In later version, Both envelope sender and From address are used to match the sender pattern. Either envelope sender or From address matches the sender pattern, the email will be re-routed.

• Match either envelope sender or From address (recommended): user@domain;
• Match the envelope sender address only: sender: user@domain;
• Match the From address only: from: user@domain.
• Match the null address: <> or sender: <> or from: <>.

Advanced Options in Sender Based Routing Rule¶

Besides Sender Condition, you can also add more conditions such as Header, Sender Group, Recipient and Subject. The email message will be re-routed to specified Send Connector while the rule matches all conditions.

Exchange Transport Rule Based Routing and Header Conditions¶

If you would create more complex conditions that "Sender Based Routing Manager" doesn’t support, you can combine Exchange built-in Transport Rule and Header Condition like this:

Open Exchange Admin Center (https://yourserver/ecp) -> mail flow -> rules

• Click plus sign and create a new rule;
• Click "more options";
• Click "add conditions", add the conditions you want;
• In this rule, “subject or body text includes ‘reroute’ word” is added as a test condition;
• Then click "add action" -> "Modify the message properties" -> "Set the message header to this value"
• Header name is set to "X-Reroute-Message", value is set to "yes"
• Save this transport rule.

Then create a rule in "Sender Based Routing Manager" like this:

• Click Routing Rules -> New;
• Input a meaningful description for this rule;
• Select "if the sender address matches the following pattern";
• Input *@mysenderdomain.com in Sender Address, sender address supports wildcard (* and ?);
• Select “and the email contains one of the following headers”;
• Add X-Reroute-Message: yes to Headers List;
• Input mysenderdomain.com.sbr in Address Space, this is the address space you have added in your Send Connector.

Combining with above Transport Rule and Header Conditions, the emails from *@mysenderdomain.com with subject or body text including “reroute” will be re-routed to “mysenderdomain.com.sbr” Send Connector.

Limitation in Exchange 2007 - 2013¶

As I mentioned, in Exchange Server 2007 - 2013, you should use a smart host (Route mail through smart hosts) in Customized Send Connector, otherwise your email will get SMTPSEND.DNS.NonExistentDomain error.

Therefore, you should consider this limitation, and create the proper Send Connector and Router Rule.

For example, if you want to relay emails like this:

• Relay all emails from *@mysenderdomain.com by MX lookup (MX record associated with recipient domain);
• Relay other emails by a smart host (Route mail through smart hosts).

You cannot create a Customized Send Connector to relay the emails from *@mysenderdomain.com (Because DNS MX lookup is not supported).

You should create a Customized Send Connector named "not.mysenderdomain.com.sbr", set smart host in this Send Connector, and then set a rule like this:

• Select "if the sender address doesn't match the following pattern";
• Input *@mysenderdomain.com in Sender Address;
• Input not.mysenderdomain.com.sbr in Address Space.

With above settings, all emails from *@mysenderdomain.com are relayed by Default Send Connector (DNS MX lookup), and other emails are relayed by Customized Send Connector (smart host).

Route Internal Recipient in Organization¶

By default, SBR doesn’t reroute the internal recipient in your organization. If you want to reroute internal recipient, you should specify the recipients explicitly by Add more conditions -> Recipient Condition.

For example, you want to reroute all emails to internal user, you should select One of recipient in the list or All recipient in the list, and input *@yourdomain to the list.

Use Header Condition to Prevent Mail Dead Loop¶

In some cases, you need to route the email to third-party server by customized Send Connector, after third-party server processed the email, the email will be sent back to your server, then your server sends it by default Send Connector. In this case, you must enable "Add the following header to prevent email dead loop" option.

It works like this:

• SBR checks the inbound email, if the specified header exists, doesn’t route this email, let default Send Connector to handle it;
• If the specified header doesn’t exist, SBR added the specified header to the email, then route it to customized Send Connector.
• Because the specified header has been added for routed email, so it prevents the email rerouted at next time again.

It is recommended to use same Header on multiple servers.

There is an alternative solution:

If your third-party server adds a special header automatically after the email has been processed, then you can select and the email doesn't contain all of the following headers in your rule, and add the specified header to the header list. It means “if the header exists, then SBR won’t reroute the email”.

Advanced Send Connector Address Space Setting¶

If you want to reroute the email to multiple Send Connectors based on recipient address as well, you can add multiple address spaces in your Send Connector like this.

• Click “Address Space”;
• Set different Send Connectors for different address spaces.

Above setting means:

• If the recipient address is *@emailarchitect.net, then reroute the email to emailarchitect.net.sbr Send Connector;
• If the recipient address is *@adminsystem.com, then reroute the email to adminsystem.com.sbr Send Connector;
• Reroute other emails to default Send Connector.

Deploy SBR on Multiple Servers¶

You can synchronize the configuration files on multiple servers as follows:

Install SBR on the first server, open the Sender Based Routing Manager and create routing rule(s), then click “Open Config Folder”, find rules.json and global.json in config folder, copy those files to Your other Exchange Servers\Sender Based Routing installation path\conf, then all of your Exchange Servers have the same configuration.

The default installation path is: C:\Program Files (x86)\EAExchSBR.

Install Sender Based Routing Plugin on Server Core¶

To enable Sender Based Routing on Exchange 2019 and Server Core without desktop experience installed, you should download the Installer , and then run it under DOS command or PowerShell.

Remote desktop installation is supported, but running the installer by Windows Admin Center -> PowerShell remotely is not supported.

DOS command:

eaexchsbr.exe

PowerShell:

./eaexchsbr.exe

The installer supports silent mode, you can use the following command to start silent installation.

DOS command:

start /wait eaexchsbr.exe /S

PowerShell:

start eaexchsbr.exe -ArgumentList /S -Wait

Use Routing Manager with Server Core¶

If you would like to manage Routing Rules using GUI Manager, there is an alternative solution:

You can run the installer on a client machine (Windows 7 - Windows 10) without Exchange Server installed, the Plugin management tool will be installed.

After the Sender Based Routing Manager is installed, open the manager and create routing rule(s), then click “Open Config Folder”, find rules.json and global.json in config folder, copy those files to Your Exchange Server\Sender Based Routing installation path\conf, then your Exchange Server has the same configuration.

The default installation path is: C:\Program Files (x86)\EAExchSBR.

Sender Based Routing Plugin Troubleshooting¶

If Sender Based Routing is not working properly, you can enable full debug log like this:

Verify Sender Based Routing Agent Installation¶

If there is no debug log generated after you enabled full debug log, you should verify the installation of EA Sender Based Routing Agent like this:

Open Exchange Management Shell and input:

Get-TransportAgent

press enter

You will see "EA Sender Based Routing Agent" in the output.

If there is no "EA Sender Based Routing Agent" in the output, you can try to re-run the installer directly to fix this issue, or contact our technical support team for assistance.

Restart-Service "MSExchangeTransport"

Free Email Support¶

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Support@EmailArchitect.NET

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