postfix/master[30767]: fatal: 0.0.0.0:n: Servname not supported for ai_socktype
postfix/master[30766]: fatal: daemon initialization failure
postfix/postfix-script[30768]: fatal: mail system startup failed
postfix.service: control process exited, code=exited status=1
Mail Transport Agent. -- Subject: Unit postfix.service has failed -- Defined-By: system
[root@mail ~]# postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
broken_sasl_auth_clients = yes
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
postconf -n
home_mailbox = mail/
html_directory = no
inet_interfaces = all
inet_protocols = all
mail_owner = postfix
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mydomain = example.com< real domain name is here
myhostname = mail.example.com <<<--real dn is here
mynetworks = 127.0.0.0/8
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.10.1/README_FILES
sample_directory = /usr/share/doc/postfix-2.10.1/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
vsmtp_tls_note_starttls_offer = yes
smtp_tls_security_level = may
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_tls_cert_file = /etc/postfix/ssl/server.crt
smtpd_tls_key_file = /etc/postfix/ssl/server.key
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_security_level = may
smtpd_tls_session_cache_timeout = 3600s
unknown_local_recipient_reject_code = 550
Somehow I had pasted a 2nd "smtp inet n - n - - smtpd " line in master.cf, while searching with nano with 'ctl w'. Removing the offending line, removed the error and postfix restarts normally again.