我正在使用amazon Ec2带有centos 6.4. 我试过这个，我得到了错误
echo "hello" | sendmail mymail@example.com
sendmail: Cannot open mail:25
我该如何解决该错误
$ ls -l /usr/sbin/sendmail
139512 lrwxrwxrwx 1 root root 21 Jul 1 15:13 /usr/sbin/sendmail -> /etc/alternatives/mta
$ man mta
No manual entry for mta