See Documentation Chapter 4.5.8
All SMTP checks are disabled for those entries (e. g. Greylisting, SPF, RBL, …)
All sites or settings are not releasing
Configuration >> Mail Proxy >> Whitelist
Mar 15 23:30:53 security postfix/postscreen[18508]: NOQUEUE: reject: RCPT from [63.141.250.42]:52154: 550 5.7.1 Service unavailable; client [63.141.250.42] blocked using dnsbl.spfbl.net; from=<admin@syscola.com.br>, to=<juliano@iwebhosting.com.br>, proto=ESMTP, helo=<servidor.syscola.com.br>
All SMTP checks are disabled for those entries (e. g. Greylisting, SPF, RBL, …)
All sites or settings are not releasing
Configuration >> Mail Proxy >> Whitelist
Mar 15 23:30:53 security postfix/postscreen[18508]: NOQUEUE: reject: RCPT from [63.141.250.42]:52154: 550 5.7.1 Service unavailable; client [63.141.250.42] blocked using dnsbl.spfbl.net; from=<admin@syscola.com.br>, to=<juliano@iwebhosting.com.br>, proto=ESMTP, helo=<servidor.syscola.com.br>