# telnet atyu30.com 25
Trying 10.0.0.200...
Connected to atyu30.com.
Escape character is '^]'.
Connection closed by foreign host.
#

# netstat -ant | grep 25
tcp        0      0  *.25                   *.*                    LISTEN
tcp6       0      0  *.25                   *.*                    LISTEN
# tail /var/log/maillog
Sep 18 22:08:10 mail postfix/master[19147]: warning: process /usr/local/libexec/postfix/smtpd pid 24353 exit status 1
Sep 18 22:08:10 mail postfix/master[19147]: warning: /usr/local/libexec/postfix/smtpd: bad command startup -- throttling
Sep 18 22:09:10 mail postfix/smtpd[15148]: warning: SASL: Connect to private/auth failed: No such file or directory
Sep 18 22:09:10 mail postfix/smtpd[15148]: fatal: no SASL authentication mechanisms
Sep 18 22:09:11 mail postfix/master[19147]: warning: process /usr/local/libexec/postfix/smtpd pid 15148 exit status 1
Sep 18 22:09:11 mail postfix/master[19147]: warning: /usr/local/libexec/postfix/smtpd: bad command startup -- throttling
Sep 18 22:10:12 mail postfix/smtpd[6498]: warning: SASL: Connect to private/auth failed: No such file or directory
Sep 18 22:10:12 mail postfix/smtpd[6498]: fatal: no SASL authentication mechanisms
Sep 18 22:10:13 mail postfix/master[19147]: warning: process /usr/local/libexec/postfix/smtpd pid 6498 exit status 1
Sep 18 22:10:13 mail postfix/master[19147]: warning: /usr/local/libexec/postfix/smtpd: bad command startup -- throttling