hey friends, I don't know what happened the postfix has stopped sending mails to outside world but I am able to receive the mails from outside world .The postfix is able to send the mails within the Lan but not to the outside world. yestarday i did make some changes to my server I am using FC3 like disabling root access on every terminal as there were some attempts to hack the computer so I thought disabling root access on every terminal will make hacking little difficult. I also did chattr +i /etc/services . But today I remove the chattr on /etc/services. The error while sending mails to outside world : Aug 2 10:34:41 mail postfix/smtp[4598]: fatal: unknown service: smtp/tcp Aug 2 10:34:42 mail postfix/qmgr[3172]: warning: premature end-of-input on private/smtp socket while reading input attribute name Aug 2 10:34:42 mail postfix/qmgr[3172]: warning: private/smtp socket: malformed response Aug 2 10:34:42 mail postfix/qmgr[3172]: warning: transport smtp failure -- see a previous warning/fatal/panic logfile record for the problem description Aug 2 10:34:42 mail postfix/master[3161]: warning: process /usr/libexec/postfix/smtp pid 4598 exit status 1 Aug 2 10:34:42 mail postfix/master[3161]: warning: /usr/libexec/postfix/smtp: bad command startup -- throttling the /usr/lib/sasl2/smptd.conf file pwcheck_method: saslauthd mech_list: plain login I am using the latest kernel and my system is upto date through yum.I am not using any 3rd party utility for scanning mails like MailScanner or Amavis-new. The master.cf of my computer smtp inet n - n - - smtpd #smtps inet n - n - - smtpd # -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes #submission inet n - n - - smtpd # -o smtpd_enforce_tls=yes -o smtpd_sasl_auth_enable=yes -o smtpd_etrn_restrictions=reject #628 inet n - n - - qmqpd pickup fifo n - n 60 1 pickup cleanup unix n - n - 0 cleanup qmgr fifo n - n 300 1 qmgr #qmgr fifo n - n 300 1 oqmgr #tlsmgr fifo - - n 300 1 tlsmgr rewrite unix - - n - - trivial-rewrite bounce unix - - n - 0 bounce defer unix - - n - 0 bounce trace unix - - n - 0 bounce verify unix - - n - 1 verify flush unix n - n 1000? 0 flush proxymap unix - - n - - proxymap smtp unix - - n - - smtp relay unix - - n - - smtp # -o smtp_helo_timeout=5 -o smtp_connect_timeout=5 showq unix n - n - - showq error unix - - n - - error local unix - n n - - local virtual unix - n n - - virtual lmtp unix - - n - - lmtp anvil unix - - n - 1 anvil # # Interfaces to non-Postfix software. Be sure to examine the manual # pages of the non-Postfix software to find out what options it wants. # # maildrop. See the Postfix MAILDROP_README file for details. # maildrop unix - n n - - pipe flags=DRhu user=vmail argv=/usr/local/bin/maildrop -d ${recipient} # # The Cyrus deliver program has changed incompatibly, multiple times. # old-cyrus unix - n n - - pipe flags=R user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -m ${extension} ${user} # Cyrus 2.1.5 (Amos Gouaux) # Also specify in main.cf: cyrus_destination_recipient_limit=1 cyrus unix - n n - - pipe user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -r ${sender} -m ${extension} ${user} uucp unix - n n - - pipe flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient) ifmail unix - n n - - pipe flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient) bsmtp unix - n n - - pipe flags=Fq. user=foo argv=/usr/local/sbin/bsmtp -f $sender $nexthop $recipient I did not make any changes in the master.cf but ran postfix upgrade-configuration command . 2bounce_notice_recipient = postmaster access_map_reject_code = 554 address_verify_default_transport = $default_transport address_verify_local_transport = $local_transport address_verify_map = address_verify_negative_cache = yes address_verify_negative_expire_time = 3d address_verify_negative_refresh_time = 3h address_verify_poll_count = 3 address_verify_poll_delay = 3s address_verify_positive_expire_time = 31d address_verify_positive_refresh_time = 7d address_verify_relay_transport = $relay_transport address_verify_relayhost = $relayhost address_verify_sender = postmaster address_verify_service_name = verify address_verify_transport_maps = $transport_maps address_verify_virtual_transport = $virtual_transport alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases allow_mail_to_commands = alias, forward allow_mail_to_files = alias, forward allow_min_user = no allow_percent_hack = yes allow_untrusted_routing = no alternate_config_directories = always_bcc = append_at_myorigin = yes append_dot_mydomain = yes application_event_drain_time = 100s backwards_bounce_logfile_compatibility = yes berkeley_db_create_buffer_size = 16777216 berkeley_db_read_buffer_size = 131072 best_mx_transport = biff = yes body_checks = body_checks_size_limit = 51200 bounce_notice_recipient = postmaster bounce_queue_lifetime = 5d bounce_service_name = bounce bounce_size_limit = 50000 broken_sasl_auth_clients = yes canonical_maps = cleanup_service_name = cleanup command_directory = /usr/sbin command_expansion_filter = 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ command_time_limit = 1000s config_directory = /etc/postfix content_filter = daemon_directory = /usr/libexec/postfix daemon_timeout = 18000s debug_peer_level = 2 debug_peer_list = default_database_type = hash default_delivery_slot_cost = 5 default_delivery_slot_discount = 50 default_delivery_slot_loan = 3 default_destination_concurrency_limit = 20 default_destination_recipient_limit = 50 default_extra_recipient_limit = 1000 default_minimum_delivery_slots = 3 default_privs = nobody default_process_limit = 100 default_rbl_reply = $rbl_code Service unavailable; $rbl_class [$rbl_what] blocked using $rbl_domain${rbl_reason?; $rbl_reason} default_recipient_limit = 10000 default_transport = smtp default_verp_delimiters = += defer_code = 450 defer_service_name = defer defer_transports = delay_notice_recipient = postmaster delay_warning_time = 0h deliver_lock_attempts = 20 deliver_lock_delay = 1s disable_dns_lookups = no disable_mime_input_processing = no disable_mime_output_conversion = no disable_verp_bounces = no disable_vrfy_command = no dont_remove = 0 double_bounce_sender = double-bounce duplicate_filter_limit = 1000 empty_address_recipient = MAILER-DAEMON enable_errors_to = no enable_original_recipient = yes error_notice_recipient = postmaster error_service_name = error expand_owner_alias = no export_environment = TZ MAIL_CONFIG fallback_relay = fallback_transport = fast_flush_domains = $relay_domains fast_flush_purge_time = 7d fast_flush_refresh_time = 12h fault_injection_code = 0 flush_service_name = flush fork_attempts = 5 fork_delay = 1s forward_expansion_filter = 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ forward_path = $home/.forward${recipient_delimiter}${extension}, $home/.forward hash_queue_depth = 1 hash_queue_names = incoming, active, deferred, bounce, defer, flush, hold, traceheader_address_token_limit = 10240 header_checks = header_size_limit = 102400 helpful_warnings = yes home_mailbox = Maildir/ hopcount_limit = 50 html_directory = no ignore_mx_lookup_error = no import_environment = MAIL_CONFIG MAIL_DEBUG MAIL_LOGTAG TZ XAUTHORITY DISPLAY in_flow_delay = 1s inet_interfaces = all initial_destination_concurrency = 5 invalid_hostname_reject_code = 501 ipc_idle = 100s ipc_timeout = 3600s ipc_ttl = 1000s line_length_limit = 2048 lmtp_bind_address = lmtp_bind_address6 = lmtp_cache_connection = yes lmtp_connect_timeout = 0s lmtp_data_done_timeout = 600s lmtp_data_init_timeout = 120s lmtp_data_xfer_timeout = 180s lmtp_destination_concurrency_limit = $default_destination_concurrency_limit lmtp_destination_recipient_limit = $default_destination_recipient_limit lmtp_lhlo_timeout = 300s lmtp_mail_timeout = 300s lmtp_quit_timeout = 300s lmtp_rcpt_timeout = 300s lmtp_rset_timeout = 120s lmtp_sasl_auth_enable = no lmtp_sasl_password_maps = lmtp_sasl_security_options = noplaintext, noanonymous lmtp_send_xforward_command = no lmtp_skip_quit_response = no lmtp_tcp_port = 24 lmtp_xforward_timeout = 300s local_command_shell = local_destination_concurrency_limit = 2 local_destination_recipient_limit = 1 local_recipient_maps = proxy:unix:passwd.byname $alias_maps local_transport = local:$myhostname luser_relay = mail_name = Postfix mail_owner = postfix mail_release_date = 20040915 mail_spool_directory = /var/mail mail_version = 2.1.5 mailbox_command = mailbox_command_maps = mailbox_delivery_lock = fcntl, dotlock mailbox_size_limit = 51200000 mailbox_transport = mailq_path = /usr/bin/mailq.postfix manpage_directory = /usr/share/man maps_rbl_domains = maps_rbl_reject_code = 554 masquerade_classes = envelope_sender, header_sender, header_recipient masquerade_domains = sunup.net masquerade_exceptions = max_idle = 100s max_use = 100 maximal_backoff_time = 4000s maximal_queue_lifetime = 5d message_size_limit = 51200000 mime_boundary_length_limit = 2048 mime_header_checks = regexp:/etc/postfix/mime_header_checks mime_nesting_limit = 100 minimal_backoff_time = 1000s multi_recipient_bounce_reject_code = 550 mydestination = $myhostname, localhost.$mydomain, $mydomain mydomain = sunupdelhi.net myhostname = mail.sunup.net mynetworks = 192.168.1.0/24, 127.0.0.0/8 mynetworks_style = subnet myorigin = $mydomain nested_header_checks = $header_checks newaliases_path = /usr/bin/newaliases.postfix non_fqdn_reject_code = 504 notify_classes = resource, software owner_request_special = yes parent_domain_matches_subdomains = debug_peer_list,fast_flush_domains,mynetworks,permit_mx_backup_networks,qmqpd_authorized_clients,relay_domains,smtpd_access_maps permit_mx_backup_networks = pickup_service_name = pickup prepend_delivered_header = command, file, forward process_id_directory = pid propagate_unmatched_extensions = canonical, virtual proxy_interfaces = proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks qmgr_clog_warn_time = 300s qmgr_fudge_factor = 100 qmgr_message_active_limit = 20000 qmgr_message_recipient_limit = 20000 qmgr_message_recipient_minimum = 10 qmqpd_authorized_clients = qmqpd_error_delay = 1s qmqpd_timeout = 300s queue_directory = /var/spool/postfix queue_file_attribute_count_limit = 100 queue_minfree = 0 queue_run_delay = 1000s queue_service_name = qmgr rbl_reply_maps = readme_directory = /usr/share/doc/postfix-2.1.5/README_FILES receive_override_options = recipient_bcc_maps = recipient_canonical_maps = recipient_delimiter = + reject_code = 554 relay_clientcerts = relay_destination_concurrency_limit = $default_destination_concurrency_limit relay_destination_recipient_limit = $default_destination_recipient_limit relay_domains = $mydestination relay_domains_reject_code = 554 relay_recipient_maps = relay_transport = relay relayhost = xxx.xxxx.xxxxx(my ISP server) relocated_maps = require_home_directory = no resolve_dequoted_address = yes resolve_null_domain = no rewrite_service_name = rewrite sample_directory = /usr/share/doc/postfix-2.1.5/samples sender_based_routing = no sender_bcc_maps = sender_canonical_maps = sendmail_path = /usr/sbin/sendmail.postfix service_throttle_time = 60s setgid_group = postdrop show_user_unknown_table_name = yes showq_service_name = showq smtp_always_send_ehlo = yes smtp_bind_address = smtp_bind_address6 = smtp_connect_timeout = 30s smtp_data_done_timeout = 600s smtp_data_init_timeout = 120s smtp_data_xfer_timeout = 180s smtp_defer_if_no_mx_address_found = no smtp_destination_concurrency_limit = $default_destination_concurrency_limit smtp_destination_recipient_limit = $default_destination_recipient_limit smtp_enforce_tls = no smtp_helo_name = $myhostname smtp_helo_timeout = 300s smtp_host_lookup = dns smtp_line_length_limit = 990 smtp_mail_timeout = 300s smtp_mx_address_limit = 0 smtp_mx_session_limit = 2 smtp_never_send_ehlo = no smtp_pix_workaround_delay_time = 10s smtp_pix_workaround_threshold_time = 500s smtp_quit_timeout = 300s smtp_quote_rfc821_envelope = yes smtp_randomize_addresses = yes smtp_rcpt_timeout = 300s smtp_rset_timeout = 120s smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = noanonymous smtp_sasl_tls_security_options = $var_smtp_sasl_opts smtp_sasl_tls_verified_security_options = $var_smtp_sasl_tls_opts smtp_send_xforward_command = no smtp_skip_5xx_greeting = yes smtp_skip_quit_response = yes smtp_starttls_timeout = 300s smtp_tls_CAfile = smtp_tls_CApath = smtp_tls_cert_file = smtp_tls_cipherlist = smtp_tls_dcert_file = smtp_tls_dkey_file = $smtp_tls_dcert_file smtp_tls_enforce_peername = yes smtp_tls_key_file = $smtp_tls_cert_file smtp_tls_loglevel = 0 smtp_tls_note_starttls_offer = no smtp_tls_per_site = smtp_tls_scert_verifydepth = 5 smtp_tls_session_cache_database = smtp_tls_session_cache_timeout = 3600s smtp_use_tls = no smtp_xforward_timeout = 300s smtpd_authorized_verp_clients = $authorized_verp_clients smtpd_authorized_xclient_hosts = smtpd_authorized_xforward_hosts = smtpd_banner = $myhostname ESMTP $mail_name ($mail_version) smtpd_client_connection_count_limit = 50 smtpd_client_connection_limit_exceptions = $mynetworks smtpd_client_connection_rate_limit = 0 smtpd_client_restrictions = smtpd_data_restrictions = smtpd_delay_reject = yes smtpd_enforce_tls = no smtpd_error_sleep_time = 1s smtpd_etrn_restrictions = smtpd_expansion_filter = \t\40!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~ smtpd_hard_error_limit = 20 smtpd_helo_required = no smtpd_helo_restrictions = smtpd_history_flush_threshold = 100 smtpd_junk_command_limit = 100 smtpd_noop_commands = smtpd_null_access_lookup_key = <> smtpd_policy_service_max_idle = 300s smtpd_policy_service_max_ttl = 1000s smtpd_policy_service_timeout = 100s smtpd_proxy_ehlo = $myhostname smtpd_proxy_filter = smtpd_proxy_timeout = 100s smtpd_recipient_limit = 1000 smtpd_recipient_overshoot_limit = 1000 smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_invalid_hostname, reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_destination, reject_rbl_client relays.ordb.org, reject_rbl_client opm.blitzed.org, reject_rbl_client list.dsbl.org, reject_rbl_client sbl.spamhaus.org, reject_rbl_client cbl.abuseat.org, reject_rbl_client dul.dnsbl.sorbs.net, permit smtpd_reject_unlisted_recipient = yes smtpd_reject_unlisted_sender = no smtpd_restriction_classes = smtpd_sasl_application_name = smtpd smtpd_sasl_auth_enable = no smtpd_sasl_exceptions_networks = smtpd_sasl_local_domain = smtpd_sasl_security_options = noanonymous smtpd_sasl_tls_security_options = $smtpd_sasl_security_options smtpd_sender_login_maps = smtpd_sender_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unknown_sender_domain, reject_rbl_client relays.ordb.org, reject_rbl_client opm.blitzed.org, reject_rbl_client list.dsbl.org, reject_rbl_client sbl.spamhaus.org, reject_rbl_client cbl.abuseat.org, reject_rbl_client dul.dsnbl.sorbs.net, permit smtpd_soft_error_limit = 10 smtpd_starttls_timeout = 300s smtpd_timeout = 300s smtpd_tls_CAfile = smtpd_tls_CApath = smtpd_tls_ask_ccert = no smtpd_tls_auth_only = no smtpd_tls_ccert_verifydepth = 5 smtpd_tls_cert_file = smtpd_tls_cipherlist = smtpd_tls_dcert_file = smtpd_tls_dh1024_param_file = smtpd_tls_dh512_param_file = smtpd_tls_dkey_file = $smtpd_tls_dcert_file smtpd_tls_key_file = $smtpd_tls_cert_file smtpd_tls_loglevel = 0 smtpd_tls_received_header = no smtpd_tls_req_ccert = no smtpd_tls_session_cache_database = smtpd_tls_session_cache_timeout = 3600s smtpd_tls_wrappermode = no smtpd_use_tls = no soft_bounce = no stale_lock_time = 500s strict_7bit_headers = no strict_8bitmime = no strict_8bitmime_body = no strict_mime_encoding_domain = no strict_rfc821_envelopes = no sun_mailtool_compatibility = no swap_bangpath = yes syslog_facility = mail syslog_name = postfix tls_daemon_random_bytes = 32 tls_daemon_random_source = tls_ipv6_version = 1.26 tls_random_bytes = 32 tls_random_exchange_name = ${config_directory}/prng_exch tls_random_prng_update_period = 60s tls_random_reseed_period = 3600s tls_random_source = trace_service_name = trace transport_maps = transport_retry_time = 60s trigger_timeout = 10s undisclosed_recipients_header = To: undisclosed-recipients:; unknown_address_reject_code = 450 unknown_client_reject_code = 450 unknown_hostname_reject_code = 450 unknown_local_recipient_reject_code = 550 unknown_relay_recipient_reject_code = 550 unknown_virtual_alias_reject_code = 550 unknown_virtual_mailbox_reject_code = 550 unverified_recipient_reject_code = 450 unverified_sender_reject_code = 450 verp_delimiter_filter = -=+ virtual_alias_domains = $virtual_alias_maps virtual_alias_expansion_limit = 1000 virtual_alias_maps = $virtual_maps virtual_alias_recursion_limit = 1000 virtual_destination_concurrency_limit = $default_destination_concurrency_limit virtual_destination_recipient_limit = $default_destination_recipient_limit virtual_gid_maps = virtual_mailbox_base = virtual_mailbox_domains = $virtual_mailbox_maps virtual_mailbox_limit = 51200000 virtual_mailbox_lock = fcntl virtual_mailbox_maps = virtual_minimum_uid = 100 virtual_transport = virtual virtual_uid_maps = Please let me know if any other inputs are needed. Thanks & Regards Ankush Grover