Listing 3 Postfix main.cf -- baseline

# Whether to generate 4.x.x or 5.x.x SMTP error codes
# Set to yes only while testing new REJECT rules (4.x.x error codes)
soft_bounce = no
# Root directory for various PostFix message spools
queue_directory = /var/spool/postfix
# Where to find PostFix administrative helper binaries
command_directory = /usr/local/sbin
# Where to find PostFix daemon binaries
daemon_directory = /usr/local/libexec/postfix
# Where to locate the Sendmail API
sendmail_path = /usr/lib/sendmail
# Where the newaliases command is found
newaliases_path = /usr/bin/newaliases
# Where the mailq command is found
mailq_path = /usr/bin/mailq
# Where man pages are located
manpage_directory = /usr/local/man
# Where sample configs are stored
sample_directory = /usr/local/etc/postfix/samples
# Where README files are stored
readme_directory = /usr/local/etc/postfix/READMEs
# Userid/Groupid to run under
mail_owner = postfix
setgid_group = postdrop
# FQDNs that this local host is known by
myhostname = smtp-gate.mail.domain
myhostname = smtp-gate.mail.domain.kntr
# Domains that local host is part of
mydomain = mail.domain
# Domain to put on outbound emails from non-FQDN user names
myorigin = $mydomain
# Message to display to SMTP clients
smtpd_banner = mail3.mail.domain Unsolicited Email and Unauthorized \
  Relaying Not Permitted
# Reject code for invalid addresses
unknown_local_recipient_reject_code = 550
# Mapfile of IPs relay for
mynetworks = dbm:/usr/local/etc/postfix/network_table
# Mapfile of logical domains to relay for
relay_domains = dbm:/usr/local/etc/postfix/relay_domains
# Custom mail routing definitions
transport_maps = dbm:/usr/local/etc/postfix/transport_map
# Where to deliver local mail to
mail_spool_directory = /var/mail
# user alias lookups
alias_maps = dbm:/usr/local/etc/postfix/postfix_aliases
alias_database = dbm:/usr/local/etc/postfix/postfix_aliases
# Inbound virtual user mappings
virtual_alias_maps = dbm:/usr/local/etc/postfix/virtual_users