[Email DLP] How to Check Existing Connectors and Transport Rules in Exchange Online – HENNGE One Help Center

Target

Administrators of HENNGE Email DLP

Description

This article explains the impact of existing connectors and transport rules on mail flow when connecting HENNGE Email DLP to Exchange Online, as well as how to check these settings.

Notes

When connecting HENNGE Email DLP to Exchange Online, new connectors and transport rules will be created. If existing settings are present, they may affect the use of HENNGE Email DLP or prevent a successful connection. Please make sure to follow this procedure before performing the Email DLP connection steps.
The content of this article is based on product specifications as of November 2026 and is subject to change without notice.

Preparation

To determine whether existing settings will have any effect, check the current connector and rule settings from the following Exchange admin center links.

Connectors: https://admin.cloud.microsoft/exchange?#/connectors (external link)
Transport rules: https://admin.cloud.microsoft/exchange?#/transportrules (external link)

If there are no existing settings, or only disabled settings exist, you may end this procedure here.

Procedure

1. How to Check Outbound Connector Settings

Follow the steps below to check outbound connectors.
Since outbound connectors may affect the use of Email DLP, all must be checked.

Access "Connectors" in the Exchange admin center.
https://admin.cloud.microsoft/exchange?#/connectors (external link)
Click on an existing connector. If the [Mail flow scenario] is as follows, it is an outbound connector.
From: Office 365
To: Partner organization or organization's mail server

■ Settings that must be checked together with rules

Outbound connectors where the "When to use the connector" condition is set to "Only when a transport rule redirects messages to this connector".

* This setting only works when use is defined via a rule. Therefore, in the subsequent rule check procedure, you must also check whether there are any rules specifying this connector as the destination and their conditions.

■ Settings that require confirmation for impact on Email DLP usage

Outbound connectors where the "When to use the connector" condition is set to "Only when email messages are sent to these domains".

If this setting exists, emails matching the condition may not be properly routed to HENNGE Email DLP. Before performing the Email DLP connection procedure, please send a screenshot showing the setting values to your HENNGE implementation support representative.

2. How to Check Inbound Connector Settings

Follow the steps below to check inbound connectors.

Access "Connectors" in the Exchange admin center.
https://admin.cloud.microsoft/exchange?#/connectors (external link)
Click on an existing connector. If the [Mail flow scenario] is as follows, it is an inbound connector.
From: Partner organization or organization's mail server
To: Office 365

■ Settings that do not require confirmation for impact on Email DLP usage

If the only operation is sending from the sender to your own email address (internal recipients), there is no impact on the use of Email DLP. Therefore, no further confirmation is required.

■ Settings that require confirmation for impact on Email DLP usage

If there is an operation where emails are sent or relayed to external recipients via the inbound connector

Whether emails passing through the inbound connector are "internal only" or "including external (relay)" cannot be determined from the Exchange Online settings screen. Please check the sender's (SMTP client, etc.) settings and your actual email sending operations.
If you relay emails to external recipients via the inbound connector, system emails, etc. will also be subject to HENNGE Email DLP, which may cause delivery delays.
Due to Exchange Online specifications, emails passing through the inbound connector may not be subject to Exchange Online's sending limits. If a large volume of system emails, etc. are routed to HENNGE Email DLP as is, there is a risk of exceeding the DLP sending limit and causing delivery errors.
Troubleshooting outbound message limits and blocked users in Exchange Online
[Email DLP] About sending limits for the service

If this setting exists, please configure the settings so that the relevant emails are excluded from routing to Email DLP.
Exclude specific senders' emails from passing through HENNGE Email DLP (Microsoft 365)

3. How to Check Rule Settings

Access "Rules" in the Exchange admin center.
https://admin.cloud.microsoft/exchange?#/transportrules (external link)

■ Settings that do not require confirmation for impact on Email DLP usage

If only rules that define processing for email receiving are set within transport rules, there is no impact on the use of Email DLP. Therefore, no further confirmation is required.

■ Settings that require confirmation for impact on Email DLP usage

If there are active transport rules that change the sending route for outbound emails, such as external forwarding or routing to a specific connector, it may affect the use of Email DLP.
If you are unsure about the impact or the settings, please send a screenshot showing the detailed setting values for all outbound connectors and rules to your HENNGE implementation support representative.

Reference Information

If there are many connector and transport rule settings, you can also output the contents using the following commands. If you need to share settings with your HENNGE representative, you may send the command results to your implementation representative.

Launch PowerShell with administrator privileges.
Connect to Exchange Online.
Command
```
Connect-ExchangeOnline
```

Copy and paste the following command into PowerShell and execute it as is.
* A file named ExchangeSettings_Summary.txt will be created on your desktop.
Command

$outputPath = "$HOME\Desktop"
if (!(Test-Path $outputPath)) { $outputPath = "$HOME/Desktop" }

& {
    Write-Output "=========================================="
    Write-Output "   Transport Rule Details List"
    Write-Output "=========================================="
    Get-TransportRule | Format-List

    Write-Output "=========================================="
    Write-Output "   Inbound Connector Details List"
    Write-Output "=========================================="
    Get-InboundConnector | Format-List

    Write-Output "=========================================="
    Write-Output "   Outbound Connector Details List"
    Write-Output "=========================================="
    Get-OutboundConnector -IncludeTestModeConnectors $true | Format-List
} | Out-File -FilePath "$outputPath\ExchangeSettings_Summary.txt" -Encoding utf8