Postfix and additional headers in log file

To include Subject into postfix log file add to main.cf:

header_checks = regexp:/etc/postfix/header_checks

Then create file /etc/postfix/header_checks and add the following:

/^Subject:/ WARN

Restart postfix service.

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To include TLS info into postfix log file in addtition to the above add the following to /etc/postfix/header_checks:

/^Received:/ WARN

Restart postfix service.

Then you will get lock icon in the addition info email modal: