Centos 6.4x64 postfix email system and dovecot pop3 settings

First MX resolution
A records mxdomain 188.188.188.188
MX @ mxdomain.xxx.com
// Postfix 2.6.6
Yum install postfix

Vi/etc/postfix/main. cf

Myhostname = mxdomain.xxx.com
Mydomain = xxx.com
Myorigin = $ mydomain // The domain name after.
Inet_interfaces = all // accept requests from all networks
Mydestination = $ myhostname, localhost. $ mydomain, localhost, $ mydomain
Relay_domains = $ mydestination
Mynetworks = 168.100.189.0/28,127.0 .0.0/8
Home_mailbox = Maildir/
Smtpd_banner = $ myhostname ESMTP unknow
Smtpd_sasl_auth_enable = yes
Smtpd_sasl_type = dovecot
Smtpd_sasl_path = private/auth
Smtpd_sasl_local_domain = $ myhostname
Smtpd_sasl_security_options = noanonymous
Smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
Message _ size_limit = 15728640

Mkdir/etc/skel/Maildir
Chmod 700/etc/skel/Maildir

// Dovecot 2.0.9

Auth_mechanic isms = plain login // conf. d/10-auth.conf
Login_trusted_networks = 0.0.0.0/0
Mail_location = maildir :~ /Maildir // conf. d/10-mail.conf
Mbox_write_locks = fcntl
Passdb {
Driver = pam
}
Service auth {// conf. d/10-master.conf
Unix_listener/var/spool/postfix/private/auth {
Group = postfix
Mode = 0660
User = postfix
}
}
Ssl = no
Ssl_cert = ssl_key = userdb {
Driver = passwd
}