After enabled peer debug found this
Jul 26 21:05:21 estafeta postfix/smtpd[9928]: >
lists.isc.org[149.20.1.60]: 530 5.7.0 Must issue a STARTTLS command
first
Looks like smtpd_use_tls = yes is causing this.
http://www.postfix.org/postconf.5.html#smtpd_use_tls Says:
This feature is available in Postfix 2.2 and later. With Postfix 2.3 and
later use smtpd_tls_security_level instead.
http://www.postfix.org/postconf.5.html#smtpd_tls_security_level Says:
smtpd_tls_security_level = encrypt #Forces TLS
smtpd_tls_security_level = may #Optional TLS
