All of a sudden (Monday morning - typical) we have starting getting this
error:
postfix/smtpd[4696]: lost connection after DATA (0 bytes) from XXX...
Which is resulting in the following bounce back to senders:
Server refused mail at END OF DATA - 554 5.7.1 This message has been
blocked because the return email domain is invalid.(failed to obtain DNS
record for domain sendingdomain.co.nz)
I have checked several times and changed DNS servers to test this but im
totally at a loss as to whats happening. Ive found lots of reference to
changing the MTU on the network card... but nothing that has helped me. Can
anyone please shed some light on what could be causing this issue?
Thank you!!!!
Simon
Postfix is running on VMWare VM on debian
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
body_checks = pcre:/etc/postfix/body_checks
config_directory = /etc/postfix
header_checks = pcre:/etc/postfix/header_checks
inet_interfaces = all
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
maximal_backoff_time = 2000
maximal_queue_lifetime = 1d
message_size_limit = 52428800
minimal_backoff_time = 500
mydestination = mysql:/etc/postfix/mysql-transport.cf
mydomain = newmedia.net.nz
myhostname = mx1.newmedia.net.nz
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = newmedia.net.nz
queue_run_delay = 500
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_host_lookup = native
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
smtpd_client_restrictions = check_client_access
hash:/etc/postfix/amavis_bypass
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_helo_required = yes
smtpd_recipient_restrictions = permit_mynetworks,
reject_unauth_destination, reject_unknown_sender_domain,
reject_unknown_recipient_domain, reject_invalid_hostname,
reject_non_fqdn_sender, reject_non_fqdn_recipient,
reject_rbl_client zen.spamhaus.org, check_client_access
hash:/etc/postfix/access
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = no
transport_maps = mysql:/etc/postfix/mysql-transport.cf
unknown_local_recipient_reject_code = 550
virtual_alias_maps = mysql:/etc/postfix/mysql-aliases.cf
