sasl_smtpd_mech_list = plain login but i want non-plain annoumous login ,..

it give error,.

Oct 10 12:20:40 zim01 postfix/smtpd[25637]: Anonymous TLS connection established from mailg.abc.com [192.168.15.82]: TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)
Oct 10 12:20:40 zim01 postfix/smtpd[25637]: warning: xsasl_cyrus_server_get_mechanism_list: no applicable SASL mechanisms
Oct 10 12:20:40 zim01 postfix/smtpd[25637]: fatal: no SASL authentication mechanisms <<<<
Oct 10 12:20:41 zim01 postfix/master[23453]: warning: process /opt/zimbra/postfix/libexec/smtpd pid 25637 exit status 1