In that quickie article we will setup Postfix as yandex relay that servers only local mail (emails for root) on AlmaLinux 8.
dnf install postfix mailx cyrus-sasl-plain
nano /etc/postfix/main.cf
compatibility_level = 2
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
inet_interfaces = localhost
inet_protocols = all
mydestination = $myhostname, localhost.$mydomain, localhost
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
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
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix/samples
readme_directory = /usr/share/doc/postfix/README_FILES
smtpd_tls_cert_file = /etc/pki/tls/certs/postfix.pem
smtpd_tls_key_file = /etc/pki/tls/private/postfix.key
smtpd_tls_security_level = may
smtp_tls_CApath = /etc/pki/tls/certs
smtp_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt
meta_directory = /etc/postfix
shlib_directory = /usr/lib64/postfix
myhostname = servername
mydomain = domainname.net
local_transport = error: this is a null client
myorigin = $myhostname.$mydomain
mynetworks = 127.0.0.0/8 [::1]/128
relayhost = [smtp.yandex.ru]:465
disable_dns_lookups = yes
virtual_alias_maps = hash:/etc/postfix/virtual
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = static:yourmailbox@yandex.ru:MAILBOXPASSWORD
smtp_sasl_security_options = noanonymous
smtp_tls_security_level = encrypt
smtp_tls_wrappermode = yes
sender_canonical_classes = envelope_sender,header_sender
smtp_header_checks = regexp:/etc/postfix/header_check
sender_canonical_maps = regexp:/etc/postfix/sender_canonical_maps
nano /etc/postfix/virtual
root yourmailbox@yandex.ru
nano /etc/postfix/sender_canonical_maps
/.+/ yourmailbox@yandex.ru
nano /etc/postfix/header_check
/From:.*/ REPLACE From: yourmailbox@yandex.ru
postmap /etc/postfix/virtual
systemctl start postfix && systemctl enable postfix
Send test letter via echo “Test” | mail -s “Test ” root and check your mailbox.