The built-in postfix of CentOS6 cannot be used for sending emails

CentOS6's built-in postfix cannot be sent to solve the problem. after the system's built-in rpm Package is installed with postfix, the mail-s... test fails. Maillog is as follows: May2910: 44: 04cl101postfix/pickup [31536]: BA5662A0AFC: uid0from & lt; root & gt ;... centOS 6 comes with the postfix and cannot be sent to solve the problem. after installing the postfix through the rpm package that comes with the system, execute mail-s... the test fails. Maillog: May 29 10:44:04 cl101 postfix/pickup [31536]: BA5662A0AFC: uid = 0 from = May 29 10:44:04 cl101 postfix/cleanup [31559]: BA5662A0AFC: message-id = <20130529024404.BA5662A0AFC@cl101.dev.bizcn.com> May 29 10:44:04 cl101 postfix/qmgr [31537]: BA5662A0AFC: from = , Size = 3431896, nrcpt = 1 (queue active) May 29 10:44:04 cl101 postfix/smtp [31561]: fatal: unknown service: smtp/tcpMay 29 10:44:05 cl101 postfix/qmgr [31537]: warning: private/smtp socket: malformed responseMay 29 10:44:05 cl101 postfix/qmgr [31537]: warning: transport smtp failure -- see a previous warning/fatal/panic logfile record for the problem descriptionMay 29 10:44:05 cl101 postfix/master [31534]: warning: process/usr/libexec/postfix/smtp pid 31561 exit status 1May 29 10:44:05 cl101 postfix/master [31534]: warning:/usr/libexec/postfix/smtp: bad command startup -- throttlingMay 29 10:44:05 cl101 postfix/error [31562]: BA5662A0AFC: to = , Relay = none, delay = 1.3, delays = 0.23/1/0/0.02, dsn = 4.3.0, status = deferred (unknown mail transport error) because postfix cannot read the service file. Check whether the service permission is 640: [root @ cl101 etc] # ll | grep services-rw-r -----. 1 root 641243 Nov 7 2012 services is changed to 644: [root @ cl101 etc] # ll | grep services-rw-r --. 1 root 641243 Nov 7 2012 services and try again to solve this problem.