command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
html_directory = no
inet_protocols = ipv4
queue_directory = /var/spool/postfix
readme_directory = no
sample_directory = /etc/postfix
sendmail_path = /usr/sbin/sendmail
setgid_group = postdrop
unknown_local_recipient_reject_code = 550
inet_interfaces = all
myhostname = mail.x.com
mydomain = x.com
myorigin = $mydomain
mynetworks = 42.121.0.0/16, 127.0.0.0/8
mynetworks_style = subnet
alias_maps = hash:/etc/postfix/aliases
##############################CYRUS-SASL#####################################
broken_sasl_auth_clients = yes
#smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_invalid_hostname,reject_non_fqdn_hostname,reject_unknown_sender_domain,reject_non_fqdn_sender,reject_non_fqdn_recipient,reject_unknown_recipient_domain,reject_unauth_pipelining,reject_unauth_destination, permit
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = $mydomain
smtpd_sasl_security_options = noanonymous
smtpd_sasl_path = smtpd
smtpd_banner = Welcome to our Exchange Mail Server,Warning: Version not Available!
##############################Virtual Mailbox Settings########################
virtual_mailbox_base = /home/postfix/
virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf
virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf
virtual_alias_domains =
virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf

报错信息如下：
May  6 17:12:47 mail postfix/smtpd[18347]: connect from unknown[59.108.177.3]
May  6 17:12:47 mail authdaemond: received auth request, service=smtp, authtype=login
May  6 17:12:47 mail authdaemond: authmysql: trying this module
May  6 17:12:47 mail authdaemond: SQL query: SELECT username, password, "", '1001', '1001', concat('/home/postfix/',maildir), concat('/home/postfix/',maildir), concat(quota,'s'), name, "" FROM mailbox WHERE username = 'kefu@x.com' 
May  6 17:12:47 mail authdaemond: password matches successfully
May  6 17:12:47 mail authdaemond: authmysql: sysusername=<null>, sysuserid=1001, sysgroupid=1001, homedir=/home/postfix/x.com/kefu/Maildir/, address=kefu@x.com, fullname=?.?娆у.?. maildir=/home/postfix/x.com/kefu/Maildir/, quota=52428800Ss, options=<null>
May  6 17:12:47 mail authdaemond: authmysql: clearpasswd=<null>, passwd=$1$/GTkRmQm$AmkCMmpSopWUHbTd1GmnQ1
May  6 17:12:47 mail authdaemond: Authenticated: sysusername=<null>, sysuserid=1001, sysgroupid=1001, homedir=/home/postfix/x.com/kefu/Maildir/, address=kefu@x.com, fullname=?.?娆у.?. maildir=/home/postfix/x.com/kefu/Maildir/, quota=52428800Ss, options=<null>
May  6 17:12:47 mail authdaemond: Authenticated: clearpasswd=x, passwd=$1$/GTkRmQm$AmkCMmpSopWUHbTd1GmnQ1
May  6 17:12:47 mail postfix/smtpd[18347]: NOQUEUE: reject: RCPT from unknown[x.x.x.x]: 554 5.7.1 <kernelsky@126.com>: Relay access denied; from=<kefu@x.com> to=<kernelsky@126.com> proto=ESMTP helo=<wangjingfeng>
May  6 17:12:47 mail postfix/smtpd[18347]: disconnect from unknown[x.x.x.x]


如果我把发信的ipx.x.x.x加入到mynetworks = 42.121.0.0/16, 127.0.0.0/8 x.x.x.x  这个里面就能正常发信。
但我不能所有都加啊，所以请求高手给出正确处理方法。