postfix: 550 TLS encryption required for mails from xxx (in reply to RCPT TO command)

Error mail:

The mail system

<phishing@verbraucherzentrale.nrw>: host mail.vz-nrw.de[195.8.243.17] said: 550

TLS encryption required for mails from 83.169.45.222 (in reply to RCPT TO command)

Solution: Set smtp_tls_security_level (http://www.postfix.org/postconf.5.html#smtp_tls_security_level)