postfix not response port 25 by telnet

I followed for 2 times the tutorial for Ubuntu 16.04 server perfect, but every time I postfix does not work, when I try to telnet to port 25 I get no response, while about 110 Dovecot ok ... how can I fix this?

 

netstat -tanpu |grep :25

 

Are you connecting behind a router or directly to the internet? Is your port 25 opened/forwarded?

 

----------------------------
root@serweb2:/home/adminc# netstat -tanpu |grep :25
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 1158/master
tcp6 0 0 :::25 :::* LISTEN 1158/master

 

From the local network

 

----------------
root@serweb2:/home/adminc# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
fail2ban-postfix-sasl tcp -- anywhere anywhere multiport dports smtp
fail2ban-dovecot-pop3imap tcp -- anywhere anywhere multiport dports pop3,pop3s,imap2,imaps
fail2ban-pureftpd tcp -- anywhere anywhere multiport dports ftp
fail2ban-ssh tcp -- anywhere anywhere multiport dports ssh

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain fail2ban-dovecot-pop3imap (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere

Chain fail2ban-postfix-sasl (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere

Chain fail2ban-pureftpd (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere

Chain fail2ban-ssh (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
root@serweb2:/home/adminc#

 

telnet localhost 25 working fine ?

 

check option

-o smtpd_sasl_auth_enable=no

inside /etc/postfix/master.cf file