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Issue Description

I enabled smtp_tls_connection_reuse in Postfix main.cf and saw “Cannot start TLS: handshake failure” for new emails being generated and mail flow stopped.

Cause

I later figured out based on the doc that smtp_tls_connection_reuse has dependency on tlsproxy process and that wasn’t enabled in master.cf

Fix

  • Uncommented tlsproxy line in /etc/postfix/master.cf file.
  • Restarted postfix service
systemctl restart postfix
  • Now email flow started working.

Thanks you for reading !