Error: 450 4.4.316 Connection refused (Socket error code 10061) in Email Security.cloud

Products

• Email Security.cloud

Issue/Introduction

Emails fail delivery to specific recipients with a connection refused error. The message does not appear in Track and Trace because the rejection occurs at the SMTP gateway level before the email is processed by the Broadcom infrastructure.

Environment

Email Security.cloud

Cause

The recipient mail server (or a firewall in front of it) is refusing the SMTP connection on port 25.

Resolution

Contact the recipient's mail server administrator and provide the NDR details. The administrator should perform the following:

1. Verify the SMTP service is active and listening on port 25.
2. Check firewall logs for any rules blocking connections from Broadcom/Symantec IP ranges.
3. Review mail server logs for outages or service interruptions matching the timestamp in the NDR.
4. Ensure the recipient's mail server is not rate-limiting or incorrectly filtering the connecting MTA.