SMTP Error: 450 4.7.0 TLS encryption required

Products

• Messaging Gateway

Issue/Introduction

Messages in the Messaging Gateway (SMG) delivery queue are undelivered with the SMTP status of 

450 4.7.0 TLS encryption required

Cause

The destination mail server requires TLS secured delivery of email traffic and Messaging Gateway did not attempt to negotiate TLS when delivering the message. This is likely due to opportunistic TLS not being configured for the SMG delivery MTA.

Resolution

Enable opportunistics TLS delivery as follows:

1. Go to Administration > Configuration > hostname > SMTP
2. Click the Advanced Settings button at the bottom of the page
3. Go to the Delivery tab
4. Confirm that Attempt TLS encryption for delivery of all messages is checked
5. Click Continue
6. Click Save

Once opportunistic TLS delivery is enabled, the messages will be delivered at the next queue interval.