search for: reject_unknown_hostnam

Helo hostname MUST have resolvable hostname. Crazy or not, but i use this. The _access-allow parts for server you really trust. smtpd_client_restrictions = permit_mynetworks, reject_unauth_destination, check_client_access cidr:/etc/postfix/check_client_access-allow.cidr, reject_unknown_hostname, reject_non_fqdn_hostname, reject_invalid_hostname, reject_unknown_reverse_client_hostname, check_client_access cidr:/etc/postfix/check_client_access-reject.cidr, reject_unauth_pipelining smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks, reject_una...

..._path = /usr/local/sbin/sendmail setgid_group = maildrop shlib_directory = /usr/local/lib/postfix smtp_tls_note_starttls_offer = yes smtp_use_tls = yes smtpd_delay_reject = yes smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_invalid_hostname, reject_unknown_hostname, reject_non_fqdn_hostname, reject_non_fqdn_helo_hostname, reject_invalid_helo_hostname, permit smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_hostname, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unauth_destination, reject_unauth_pipelini...

...limit = 10 smtpd_hard_error_limit = 20 smtpd_helo_required???????????? = yes disable_vrfy_command??????????? = yes non_fqdn_reject_code??????????? = 504 invalid_hostname_reject_code??? = 450 maps_rbl_reject_code??????????? = 554 alias_maps = hash:/etc/aliases reject_unknown_client?????????? = false reject_unknown_hostname???????? = false mailbox_command = /usr/local/libexec/dovecot/deliver -f "$SENDER" -a "$RECIPIENT" [root] # vi master.cf smtp????? inet? n?????? -?????? n?????? -?????? -?????? smtpd submission inet n - - - - smtpd -D ? -o smtpd_tls_security_level=encrypt ? -o smtpd_sasl_auth_...

Hi, I'm running our local school's mail server on CentOS 7, Postfix and Dovecot. We get quite a lot of spam, so I have the following sender restrictions in my /etc/postfix/main.cf: --8<------------------------------------------------------ # Restrictions SMTP smtpd_helo_restrictions = reject_unknown_helo_hostname smtpd_sender_restrictions = reject_unknown_sender_domain,