Good evening,
I was wonder if there is someone who could help point me in the right
direction so I can solve a spam problem I have.
I am running a mail server with Ubuntu + Postfix + Maia Mailguard +
Dovecot, all has been working well until recently people have started
receiving spam email that appear to be sent from my domain.
For example
From: myn...@example.com
To: myn...@example.com
Subject: Fwd: Re: Scan from a Hewlett-Packard ScanJet 1234
But the return path is along the lines of:
Return-Path: <somen...@spammer.com>
(see header and main.cf for mail servers below for more information)
Would any one have any suggestions as the best way to block these type
of emails. Some information that might be important, some of our users
work remotely and so can connect into the gateway running Dovecot and
receive (imaps) / send (smtp) (authenticated) from any location in the
world, I am not sure if this makes it harder to block the spam.
Example header of Spam:
Return-Path: <somen...@spammer.com>
Delivered-To: myn...@example.com
Received: from mail.example.com (gateway.localhost [10.0.0.1])
by mail-int (Postfix) with ESMTP id 59CC1211180
for <myn...@example.com>; Tue, 01 Aug 2012 12:00:00 +0100 (IST)
Received: from localhost (localhost [127.0.0.1])
by mail.example.com (Postfix) with ESMTP id 43EE4C0F5
for <myn...@example.com>; Tue, 01 Aug 2012 12:00:00 +0100 (IST)
Received: from mail.example.com ([127.0.0.1])
by localhost (mail.example.com [127.0.0.1]) (amavisd-maia, port 20004)
with ESMTP id 21183-01-6 for <myn...@example.com>;
Tue, 01 Aug 2012 12:00:00 +0100 (IST)
Received: from [xx.xx.xx.xx] (unknown [xx.xx.xx.xx])
by mail.example.com (Postfix) with ESMTP id 946DBC0EB
for <myn...@example.com>; Tue, 01 Aug 2012 12:00:00 +0100 (IST)
Received: from by mx1.optonline.net; Tue, 01 Aug 2012 12:00:00 +0100
Date: Tue, 01 Aug 2012 12:00:00 +0100
From: <myn...@example.com>
Reply-To: <myn...@example.com>
X-Priority: 3 (Normal)
Message-ID: <23443546456345...@example.com>
To: myn...@example.com
Subject: Fwd: Re: Scan from a Hewlett-Packard ScanJet 8702
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="----------27AF424950946E7"
X-Virus-Scanned: Maia Mailguard 1.0.2
main.cf for postfix on Gateway
~~~~~~~~~~~~~~~~~~~~~~~~~
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
### relayhost = www.example.com
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
### from previous confing file:
soft_bounce = no
queue_directory = /var/spool/postfix
mydomain = example.com
# debug_peer_level = 2
# SPAM Processing
content_filter = amavis:[127.0.0.1]:20004
## content_filter = smtp-amavis:[127.0.0.1]:20004
##queue_minfree = 24000000
notify_classes = 2bounce,resource,software
address_verify_negative_expire_time = 30h
bounce_queue_lifetime = 48h
maximal_queue_lifetime = 50h
delay_warning_time = 20h
### new things:
alias_maps = hash:/etc/aliases
myorigin = $mydomain
myhostname = mail.example.com
mynetworks = 127.0.0.0/8, 10.0.0.0/24, xx.xx.xx.xx
message_size_limit = 20971520
local_transport = error:No local mail delivery
mydestination =
# mydestination = $myhostname, localhost.$mydomain, mail.$mydomain,
local.$mydomain
local_recipient_maps =
# local_recipient_maps = hash:/etc/postfix/recipients
virtual_maps = hash:/etc/postfix/virtual
virtual_alias_maps = $virtual_maps
relay_recipient_maps = hash:/etc/postfix/relay_recipients
transport_maps = hash:/etc/postfix/transport
relay_domains = hash:/etc/postfix/relay_domains
recipient_delimiter =
smtpd_helo_required = yes
smtpd_sender_login_maps = pcre:/etc/postfix/senders_map,
hash:/etc/postfix/senders_map_other
smtpd_sender_restrictions = permit_mynetworks, check_sender_access
hash:/etc/postfix/sender_access, reject_non_fqdn_sender,
reject_unknown_sender_domain, reject_unauthenticated_se
nder_login_mismatch
## smtpd_recipient_restrictions = check_client_access,
hash:/etc/postfix/relay_clients
smtpd_recipient_restrictions = permit_mynetworks,
permit_sasl_authenticated, reject_unauth_destination,
reject_unauth_pipelining, reject_unknown_recipient_domain,
reject_unverifie
d_recipient
smtpd_data_restrictions = reject_unauth_pipelining
### 2012-03-27
# add header for authenticated mail to strip IP
smtpd_sasl_authenticated_header = yes
header_checks = regexp:/etc/postfix/header_checks.regexp
header_checks = pcre:/etc/postfix/header_checks.pcre
body_checks = pcre:/etc/postfix/body_checks
unverified_recipient_reject_code = 550
##smtpd_client_connection_count_limit = 5
#default_process_limit = 4
disable_vrfy_command = yes
##### SASL
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
##smtpd_sasl_local_domain = $mydomain
smtpd_sasl_application_name = smtpd
#broken_sasl_auth_clients = yes
##### TLS parameters
smtp_use_tls = yes
smtpd_use_tls = yes
smtp_tls_security_level = may
smtpd_tls_security_level = may
smtpd_tls_auth_only = yes
smtp_tls_note_starttls_offer = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
smtpd_tls_cert_file=/etc/ssl/private/mail_example_com.crt
smtpd_tls_key_file=/etc/ssl/private/mail_example_com.key
smtp_tls_CAfile = /etc/ssl/private/comodo-bundle.crt
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
main.cf for postfix on Gateway
~~~~~~~~~~~~~~~~~~~~~~~~~
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
myorigin = example.com
#### mydestination = example.com, localhost
### mydestination =
mynetworks = 127.0.0.0/8, 10.0.0.0/24
myhostname = mail-int
mydomain = example.com
relayhost = 10.0.0.1
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
append_dot_mydomain = no
## Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
message_size_limit = 20971520
smtpd_helo_required = yes
## TLS parameters
#smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
#smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
#smtpd_use_tls=yes
#smtpd_tls_session_cache_database = btree:${queue_directory}/smtpd_scache
#smtp_tls_session_cache_database = btree:${queue_directory}/smtp_scache
## See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
## information on enabling SSL in the smtp client.
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
### mailbox_transport = dovecot
virtual_transport = dovecot
virtual_mailbox_base = /home/MAIL
virtual_mailbox_maps = ldap:/etc/postfix/ldap-accounts.cf
virtual_mailbox_domains = example.com
virtual_domain = example.com
virtual_minimum_uid = 30000
virtual_uid_maps = static:500
virtual_gid_maps = static:500
virtual_alias_maps = hash:/etc/postfix/aliases-virtual,
ldap:/etc/postfix/ldap-aliases.cf
#allow_mail_to_files = alias
allow_mail_to_commands = alias
#alias_maps = hash:/etc/postfix/aliases
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
## Dovecot Deliver:
#mailbox_command = /usr/local/libexec/dovecot/deliver
mailbox_command = /usr/lib/dovecot/deliver
dovecot_destination_recipient_limit = 1
