postfix 无法收信（Relay access denied）【已解决】

使用email@mail.xxx.com可以正常收发邮件。使用email@xxx.com发送邮件正常，但是收邮件却出现Relay access denied，并退信。
maillog:
Jul 18 00:41:13 mail postfix/smtpd[15353]: connect from blu0-omc1-s14.blu0.hotmail.com[65.55.116.25]
Jul 18 00:41:14 mail postfix/smtpd[15353]: AF12C126E04: client=blu0-omc1-s14.blu0.hotmail.com[65.55.116.25]
Jul 18 00:41:15 mail postfix/smtpd[15353]: AF12C126E04: reject: RCPT from blu0-omc1-s14.blu0.hotmail.com[65.55.116.25]: 554 <email@xxx.com>: Relay access denied; from=<adisonray@hotmail.com> to=<email@xxx.com> proto=ESMTP helo=<blu0-omc1-s14.blu0.hotmail.com>
Jul 18 00:41:16 mail popper[15357]: (v4.0.8) Unable to get canonical name of client 116.52.33.231: Unknown host (1)
Jul 18 00:41:16 mail popper[15357]: (v4.0.8) Servicing request from "116.52.33.231" at 116.52.33.231
Jul 18 00:41:16 mail popper[15357]: Stats: email 0 0 0 0 116.52.33.231 116.52.33.231
Jul 18 00:41:17 mail postfix/smtpd[15353]: disconnect from blu0-omc1-s14.blu0.hotmail.com[65.55.116.25]
请求帮助！谢谢！

　　　　　　

main.cf

myhostname = mail.xxx.com
mydomain = xxx.com
inet_interfaces = all
myorigin = $myhostname
mydestination = $myhostname, $mydomain
mynetworks_style = subnet
mynetworks = 168.100.189.0/28, 127.0.0.0/8
relay_domains = $mydestination

##SMTP###
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = ' '
smtpd_sasl_security_options = noanonymous
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_client_restrictions = permit_sasl_authenticated

做过：
xxx.com ， www.xxx.com ， mail.xxx.com 的A记录各一条。
xxx.com MX in mail.xxx.com 的记录一条。　　　　　　

>> Jul 18 00:41:16 mail popper[15357]: (v4.0.8) Unable to get canonical name of client 116.52.33.231: Unknown host (1)
>> Jul 18 00:41:16 mail popper[15357]: (v4.0.8) Servicing request from "116.52.33.231" at 116.52.33.231
客户端没有验证吗?　　　　　　

SMTP认证用的是SASL。POP3需要认证吗？使用email@mail.xxx.com是可以正常收发的呀。　　　　　　

main.cf 中 myhostname 是如何定义的? A记录的域名需要列在这里哦　　　　　　

谢谢版主的帮助。
问题已经解决了。
myhostname ＝$myhostname , $mydomain