Out-of-Office Emails Fail from Office 365 When Using Email Security.Cloud

Products

• Email Security.cloud

Issue/Introduction

When routing mail from Office 365 through Symantec Email Security.Cloud, Out-of-Office notifications and other automatic replies are not delivered successfully.

Environment

Microsoft Office 365 (Exchange Online)

Symantec Email Security.Cloud

Cause

Out-of-Office notifications are generated with a blank (null) sender address. Symantec Email Security.Cloud only accepts outbound relays from Office 365 if the domain in the Mail From address is provisioned on the customer’s account. Since automatic replies use a null sender, they cannot be relayed through the service.

Resolution

To ensure Out-of-Office and automatic replies are delivered, you must configure Office 365 to bypass the Symantec smarthost and send these messages directly via DNS MX records. This is achieved by:

• Creating a dedicated outbound connector in Exchange Online.
• Configuring a transport rule to redirect automatic replies through this connector.

If further assistance is required, Microsoft Exchange Online support can provide guidance.

 

Step 1: Create an Outbound Connector for DNS Routing

1. In the Office 365 Admin Center, go to Mail Flow > Connectors.

2. Click Add a connector.

3. Set:

From = Office 365

To = Partner Organization

 

4. Enter a name for the connector.

 

5. Select Use of connector = Only when a transport rule redirects messages to this connector.

 

6. Under Routing, choose Use the MX record associated with the recipient’s domain.

 

 

7. Configure Security restrictions as per your organization’s policy (defaults are acceptable).

 

8. Provide a validation email address and complete validation.

 

9. Review and create the connector.

 

 

 

 

Step 2: Create a Transport Rule for Automatic Replies

 

1. In the Office 365 Admin Center, go to Mail Flow > Rules.

2. Click Add a new transport rule.

3. Provide a descriptive name (e.g., Redirect Automatic Replies via DNS or Automatic reply via DNS).

4. Configure conditions:

Apply this rule if… → The message properties include the message type = Automatic reply.

 

5. Configure the action:

Do the following… → Redirect the message to the following connector → select the connector created in Step 1.

 

6. Save the rule.

 

 

Notes:

The interface in the Microsoft 365 Admin Center may differ slightly due to updates by Microsoft.

This configuration applies only to automatic replies. Regular mail continues to route through Symantec Email Security.Cloud.