The article shows the very basic configuration accepting mail from localhost only and serving several domains

smtpd_banner = $myhostname ESMTP $mail_name (Raspbian)
biff = no
append_dot_mydomain = no
readme_directory = no
compatibility_level = 2
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = skisport.org.ua
mydomain = skisport.org.ua
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = $myhostname, $mydomain, localhost, localhost.localdomain, , localhost
myorigin = $mydomain
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
virtual_alias_domains = hash:/etc/postfix/virtual_domains

Alias domains file looks like:

<domain_name>    #domain

WARNING - after creation of text file need to issue following command to receive a hash file:

postmap /etc/postfix/virtual_domains