TPCF Deploy Notifications errand fails with: "SMTP TLS configuration mismatch: Not configured to use TLS over SMTP, but the mail server does support the "STARTTLS" extension"

Products

• VMware Tanzu Application Service

Issue/Introduction

When attempting to run the deploy-notifications errand, it fails with the message:

SMTP TLS configuration mismatch: Not configured to use TLS over SMTP, but the mail server does support the "STARTTLS" extension

This prevents the application from starting.

Environment

TPCF

Cause

When the notifications app starts up it will connect to the SMTP server and check if the server supports StartTLS.  Use the table below to understand what symptoms to expect based on both client and server settings.

SMTP Server	Notificaitons App	Result
Supports StartTLS	Use StartTLS protocol is enabled ( env SMTP_TLS=true )	successful StartTLS connection
StartTLS is not supported	Use StartTLS protocol is enabled ( env SMTP_TLS=true )	configuration mismatch error observed
Supports StartTLS	Use StartTLS protocol is disabled ( env SMTP_TLS=false )	configuration mismatch error observed

 

Resolution

Go to Elastic Application Runtime tile -> Email Notifications tab and configure "Use StartTLS protocol" based on the SMTP server compatibility mentioned in the table above.  For quick troubleshooting you can also toggle StartTLS by editing the notification app environment variable "SMTP_TLS" through apps manager or cf cli.  The notification app can be found in "system" org and "notifications-with-ui" space

 

if you are unsure if the smtp server supports StartTLS you can test it using this openssl command. 

openssl s_client -starttls smtp -connect <HOST-OR-IP>:<PORT>