May 22 09:27:07 vs2060074 postfix/smtpd[7928]: warning: xsasl_cyrus_server_get_mechanism_list: no applicable SASL mechanisms
May 22 09:27:07 vs2060074 postfix/smtpd[7928]: fatal: no SASL authentication mechanisms
May 22 09:27:08 vs2060074 postfix/master[6014]: warning: process /usr/libexec/postfix/smtpd pid 7928 exit status 1
May 22 09:27:08 vs2060074 postfix/master[6014]: warning: /usr/libexec/postfix/smtpd: bad command startup -- throttling

установить:
cyrus-sasl-plain
cyrus-sasl-sql


http://fedorasolved.org/server-solutions/postfix-mail-server