Messages Stuck with SMTP Error 5.7.650 (Rate Limited)

Products

• Messaging Gateway

Issue/Introduction

Outbound emails are failing to deliver and remaining in the Symantec Messaging Gateway (SMG) delivery queue. When inspecting the message status, the following SMTP response is displayed:

451 4.7.650 the mail server [IP ADDRESS] has been rate limited due to IP reputation

Cause

This error indicates that the recipient's mail server (or their third-party security provider) is actively rejecting or throttling connections from your public IP address.

This is typically triggered because your IP address has been flagged for a poor sender reputation. This is an external reputation issue and is not caused by a functional failure or misconfiguration within the SMG appliance itself.

Resolution

Because the rejection is happening at the destination gateway, the resolution must be handled between your organization and the recipient's mail administrators.