我注意到一个垃圾邮件发送者通过了 postgrey 和 SpamAssassin，这非常奇怪。我检查了一下/var/log/mail.log，发现一些可疑的行：
登录下面，或者在 Pastebin 上：http://pastebin.com/k7sKnvGE
Jul 19 07:59:06 mail postfix/smtpd[15492]: connect from unknown[37.215.63.185]
Jul 19 07:59:07 mail postfix/smtpd[15492]: NOQUEUE: reject_warning: RCPT from unknown[37.215.63.185]: 504 5.5.2 <37.215.63.185>: Helo command rejected: need fully-qualified hostname; from=<> to=<[email protected]> proto=SMTP helo=<37.215.63.185>
Jul 19 07:59:07 mail postgrey[13086]: action=pass, reason=triplet found, delay=316, client_name=unknown, client_address=37.215.63.185, [email protected]
Jul 19 07:59:07 mail postfix/smtpd[15492]: B8D5D20BDD: client=unknown[37.215.63.185]
Jul 19 07:59:09 mail postfix/cleanup[15500]: B8D5D20BDD: message-id=<>
Jul 19 07:59:09 mail postfix/qmgr[3224]: B8D5D20BDD: from=<>, size=493, nrcpt=1 (queue active)
Jul 19 07:59:09 mail amavis[11960]: (11960-14) NOTICE: reconnecting in response to: err=2006, HY000, DBD::mysql::st execute failed: MySQL server has gone away at (eval 111) line 170, <GEN39> line 9463.
Jul 19 07:59:10 mail postfix/smtpd[15492]: disconnect from unknown[37.215.63.185]
Jul 19 07:59:11 mail postfix/smtpd[15505]: connect from localhost[127.0.0.1]
Jul 19 07:59:11 mail postfix/smtpd[15505]: 96E1820C16: client=localhost[127.0.0.1]
Jul 19 07:59:11 mail postfix/cleanup[15500]: 96E1820C16: message-id=<[email protected]>
Jul 19 07:59:11 mail postfix/qmgr[3224]: 96E1820C16: from=<>, size=1166, nrcpt=1 (queue active)
Jul 19 07:59:11 mail postfix/smtpd[15505]: disconnect from localhost[127.0.0.1]
Jul 19 07:59:11 mail amavis[11960]: (11960-14) Passed CLEAN {RelayedInbound}, [37.215.63.185]:55743 <> -> <[email protected]>, Queue-ID: B8D5D20BDD, mail_id: d6hKjzEiMtex, Hits: 1.296, size: 493, queued_as: 96E1820C16, 2128 ms
Jul 19 07:59:11 mail postfix/smtp[15502]: B8D5D20BDD: to=<[email protected]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4.2, delays=2.1/0.01/0.01/2.1, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 96E1820C16)
Jul 19 07:59:11 mail postfix/qmgr[3224]: B8D5D20BDD: removed
Jul 19 07:59:11 mail dovecot: auth-worker(15508): mysql(localhost): Connected to database vimbadmin
Jul 19 07:59:11 mail dovecot: lda([email protected]): sieve: msgid=<[email protected]>: stored mail into mailbox 'INBOX'
Jul 19 07:59:11 mail postfix/pipe[15506]: 96E1820C16: to=<[email protected]>, relay=dovecot, delay=0.05, delays=0/0/0/0.04, dsn=2.0.0, status=sent (delivered via dovecot service)
Jul 19 07:59:11 mail postfix/qmgr[3224]: 96E1820C16: removed
我不知道是否有人利用该服务器来欺骗 localhost，或者 Amavis 或 MySQL 是否在我的终端出现故障，然后允许电子邮件通过。任何对此的洞察都会大大感谢！
/etc/postfix/main.cf：
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
# The first text sent to a connecting process.
smtpd_banner = $myhostname ESMTP $mail_name
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
readme_directory = no
# SASL parameters
# ---------------------------------
# Use Dovecot to authenticate.
smtpd_sasl_type = dovecot
# Referring to /var/spool/postfix/private/auth
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain =
smtpd_sasl_authenticated_header = yes
# TLS parameters
# ---------------------------------
# The default snakeoil certificate. Comment if using a purchased
# SSL certificate.
#smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
#smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
# Uncomment if using a purchased SSL certificate.
smtpd_tls_cert_file=/etc/ssl/mail.myhost.com/crt
smtpd_tls_key_file=/etc/ssl/mail.myhost.com/key
# The snakeoil self-signed certificate has no need for a CA file. But
# if you are using your own SSL certificate, then you probably have
# a CA certificate bundle from your provider. The path to that goes
# here.
smtpd_tls_CAfile=/etc/ssl/mail.myhost.com/ca-bundle
smtp_tls_note_starttls_offer = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
#smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
#smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
# Note that forcing use of TLS is going to cause breakage - most mail servers
# don't offer it and so delivery will fail, both incoming and outgoing. This is
# unfortunate given what various governmental agencies are up to these days.
#
# Enable (but don't force) all incoming smtp connections to use TLS.
smtpd_tls_security_level = may
# Enable (but don't force) all outgoing smtp connections to use TLS.
smtp_tls_security_level = may
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
# SMTPD parameters
# ---------------------------------
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
# will it be a permanent error or temporary
unknown_local_recipient_reject_code = 450
# how long to keep message on queue before return as failed.
# some have 3 days, I have 16 days as I am backup server for some people
# whom go on holiday with their server switched off.
maximal_queue_lifetime = 7d
# max and min time in seconds between retries if connection failed
minimal_backoff_time = 1000s
maximal_backoff_time = 8000s
# how long to wait when servers connect before receiving rest of data
smtp_helo_timeout = 60s
# how many address can be used in one message.
# effective stopper to mass spammers, accidental copy in whole address list
# but may restrict intentional mail shots.
smtpd_recipient_limit = 16
# how many error before back off.
smtpd_soft_error_limit = 3
# how many max errors before blocking it.
smtpd_hard_error_limit = 12
# This next set are important for determining who can send mail and relay mail
# to other servers. It is very important to get this right - accidentally producing
# an open relay that allows unauthenticated sending of mail is a Very Bad Thing.
#
# You are encouraged to read up on what exactly each of these options accomplish.
# Requirements for the HELO statement
smtpd_helo_restrictions = permit_mynetworks, warn_if_reject reject_non_fqdn_hostname, reject_invalid_hostname, permit
# Requirements for the sender details
smtpd_sender_restrictions = permit_sasl_authenticated, permit_mynetworks, warn_if_reject reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining, permit
# Requirements for the connecting server
smtpd_client_restrictions =
# Requirement for the recipient address. Note that the entry for
# "check_policy_service inet:127.0.0.1:10023" enables Postgrey.
smtpd_recipient_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, check_policy_service inet:127.0.0.1:10023, permit
smtpd_data_restrictions = reject_unauth_pipelining
# This is a new option as of Postfix 2.10, and is required in addition to
# smtpd_recipient_restrictions for things to work properly in this setup.
#smtpd_relay_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, check_policy_service inet:127.0.0.1:10023, permit
# require proper helo at connections
smtpd_helo_required = yes
# waste spammers time before rejecting them
smtpd_delay_reject = yes
disable_vrfy_command = yes
# General host and delivery info
# ----------------------------------
myhostname = mail.myhost.com
#myorigin = /etc/hostname
# Some people see issues when setting mydestination explicitly to the server
# subdomain, while leaving it empty generally doesn't hurt. So it is left empty here.
# mydestination = mail.example.com, localhost
mydestination = mail.myhost.com, localhost.localdomain, localhost
# If you have a separate web server that sends outgoing mail through this
# mailserver, you may want to add its IP address to the space-delimited list in
# mynetworks, e.g. as 10.10.10.10/32.
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
mynetworks_style = host
# This specifies where the virtual mailbox folders will be located.
virtual_mailbox_base = /var/vmail
# This is for the mailbox location for each user. The domainaliases
# map allows us to make use of Postfix Admin's domain alias feature.
#virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf, mysql:/etc/postfix/mysql_virtual_mailbox_domainaliases_maps.cf
virtual_mailbox_maps = mysql:/etc/postfix/vimb/virtual_mailbox_maps.cf
# and their user id
virtual_uid_maps = static:150
# and group id
virtual_gid_maps = static:8
# This is for aliases. The domainaliases map allows us to make
# use of Postfix Admin's domain alias feature.
#virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf, mysql:/etc/postfix/mysql_virtual_alias_domainaliases_maps.cf
virtual_alias_maps = mysql:/etc/postfix/vimb/virtual_alias_maps.cf
# This is for domain lookups.
#virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf
virtual_mailbox_domains = mysql:/etc/postfix/vimb/virtual_domains_maps.cf
alias_maps=hash:/etc/aliases
# Integration with other packages
# ---------------------------------------
# Tell postfix to hand off mail to the definition for dovecot in master.cf
virtual_transport = dovecot
#dovecot_destination_recipient_limit = 1
# Use amavis for virus and spam scanning
content_filter = amavis:[127.0.0.1]:10024
# Header manipulation
# --------------------------------------
# Getting rid of unwanted headers. See: https://posluns.com/guides/header-removal/
header_checks = regexp:/etc/postfix/header_checks
# getting rid of x-original-to
enable_original_recipient = no
/etc/postfix/master.cf：
#
# Postfix master process configuration file. For details on the format
# of the file, see the master(5) manual page (command: "man 5 master").
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ==========================================================================
smtp inet n - - - - smtpd
#smtp inet n - - - 1 postscreen
#smtpd pass - - - - - smtpd
#dnsblog unix - - - - 0 dnsblog
#tlsproxy unix - - - - 0 tlsproxy
#submission inet n - - - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_client_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#smtps inet n - - - - smtpd
# -o syslog_name=postfix/smtps
# -o smtpd_tls_wrappermode=yes
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_client_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#628 inet n - - - - qmqpd
pickup fifo n - - 60 1 pickup
-o content_filter=
-o receive_override_options=no_header_body_checks
cleanup unix n - - - 0 cleanup
qmgr fifo n - n 300 1 qmgr
#qmgr fifo n - n 300 1 oqmgr
tlsmgr unix - - - 1000? 1 tlsmgr
rewrite unix - - - - - trivial-rewrite
bounce unix - - - - 0 bounce
defer unix - - - - 0 bounce
trace unix - - - - 0 bounce
verify unix - - - - 1 verify
flush unix n - - 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - - - - smtp
relay unix - - - - - smtp
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - - - - showq
error unix - - - - - error
retry unix - - - - - error
discard unix - - - - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - - - - lmtp
anvil unix - - - - 1 anvil
scache unix - - - - 1 scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent. See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
# mailbox_transport = lmtp:inet:localhost
# virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
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=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe
flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
${nexthop} ${user}
# The next two entries integrate with Amavis for anti-virus/spam checks.
amavis unix - - - - 2 smtp
-o smtp_data_done_timeout=1200
-o smtp_send_xforward_command=yes
-o disable_dns_lookups=yes
-o max_use=20
127.0.0.1:10025 inet n - - - - smtpd
-o content_filter=
-o local_recipient_maps=
-o relay_recipient_maps=
-o smtpd_restriction_classes=
-o smtpd_delay_reject=no
-o smtpd_client_restrictions=permit_mynetworks,reject
-o smtpd_helo_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o smtpd_data_restrictions=reject_unauth_pipelining
-o smtpd_end_of_data_restrictions=
-o mynetworks=127.0.0.0/8
-o smtpd_error_sleep_time=0
-o smtpd_soft_error_limit=1001
-o smtpd_hard_error_limit=1000
-o smtpd_client_connection_count_limit=0
-o smtpd_client_connection_rate_limit=0
-o receive_override_options=no_header_body_checks,no_unknown_recipient_checks
# Integration with Dovecot - hand mail over to it for local delivery, and
# run the process under the vmail user and mail group.
dovecot unix - n n - - pipe
flags=DRhu user=vmail:mail argv=/usr/lib/dovecot/dovecot-lda -d $(recipient)
答案1
上述日志是 postfix 和 amavis 的预期行为。对于像 amavis 这样的队列内容过滤器，过滤器需要将电子邮件重新注入到 postfix。更多信息请参阅官方文档。这里对 postfix 和 amavis 的作用进行一些解释。
Jul 19 07:59:06 mail postfix/smtpd[15492]: connect from unknown[37.215.63.185]
来自 37.215.63.185 的客户端连接到您的邮件服务器。
Jul 19 07:59:07 mail postfix/smtpd[15492]: NOQUEUE: reject_warning: RCPT from unknown[37.215.63.185]: 504 5.5.2 <37.215.63.185>: Helo command rejected: need fully-qualified hostname; from=<> to=<[email protected]> proto=SMTP helo=<37.215.63.185>
Postfix 会警告你，因为 HELO 命令包含非完全限定的主机名，但它仍然会发送电子邮件，因为你指定了拒绝时发出警告在main.cf。
Jul 19 07:59:07 mail postgrey[13086]: action=pass, reason=triplet found, delay=316, client_name=unknown, client_address=37.215.63.185, [email protected]
Postgrey 不会拒绝该电子邮件，因为客户端之前已经通过了 postgrey 的检查。
Jul 19 07:59:07 mail postfix/smtpd[15492]: B8D5D20BDD: client=unknown[37.215.63.185]
Jul 19 07:59:09 mail postfix/cleanup[15500]: B8D5D20BDD: message-id=<>
Jul 19 07:59:09 mail postfix/qmgr[3224]: B8D5D20BDD: from=<>, size=493, nrcpt=1 (queue active)
Postfix 为电子邮件分配了队列 ID，因为通过了所有限制。在此阶段，posfix 已接受电子邮件。
Jul 19 07:59:09 mail amavis[11960]: (11960-14) NOTICE: reconnecting in response to: err=2006, HY000, DBD::mysql::st execute failed: MySQL server has gone away at (eval 111) line 170, <GEN39> line 9463.
Postfix 已开始将您的电子邮件传输到 amavis，然后 amavis 通知您 mysql 连接不成功。
Jul 19 07:59:10 mail postfix/smtpd[15492]: disconnect from unknown[37.215.63.185]
来自 37.215.63.185 的客户端与您的服务器断开连接，因为 Postfix 接受了电子邮件。
Jul 19 07:59:11 mail postfix/smtpd[15505]: connect from localhost[127.0.0.1]
Amavis 尝试将电子邮件重新注入端口 10025。默认情况下，Amavis 仅在电子邮件状态为 PASSED CLEAN（基于下面的日志行）时才重新注入消息。
Jul 19 07:59:11 mail postfix/smtpd[15505]: 96E1820C16: client=localhost[127.0.0.1]
Jul 19 07:59:11 mail postfix/cleanup[15500]: 96E1820C16: message-id=<[email protected]>
Jul 19 07:59:11 mail postfix/qmgr[3224]: 96E1820C16: from=<>, size=1166, nrcpt=1 (queue active)
显然，Postfix 接受了来自 amavis 的电子邮件。
Jul 19 07:59:11 mail postfix/smtpd[15505]: disconnect from localhost[127.0.0.1]
Amavis 已完成发送过程
Jul 19 07:59:11 mail amavis[11960]: (11960-14) Passed CLEAN {RelayedInbound}, [37.215.63.185]:55743 <> -> <[email protected]>, Queue-ID: B8D5D20BDD, mail_id: d6hKjzEiMtex, Hits: 1.296, size: 493, queued_as: 96E1820C16, 2128 ms
Amavis 在邮件日志中记录了他的操作。SpamAssasin 分数相对较低 (1.296)，并且该电子邮件通过了所有 amavis 检查。
Jul 19 07:59:11 mail postfix/smtp[15502]: B8D5D20BDD: to=<[email protected]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4.2, delays=2.1/0.01/0.01/2.1, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 96E1820C16)
Postfix 通知电子邮件扫描成功。
Jul 19 07:59:11 mail postfix/qmgr[3224]: B8D5D20BDD: removed
队列已移除。然后电子邮件已发送至下面的 dovecot。
Jul 19 07:59:11 mail dovecot: auth-worker(15508): mysql(localhost): Connected to database vimbadmin
Jul 19 07:59:11 mail dovecot: lda([email protected]): sieve: msgid=<[email protected]>: stored mail into mailbox 'INBOX'
Jul 19 07:59:11 mail postfix/pipe[15506]: 96E1820C16: to=<[email protected]>, relay=dovecot, delay=0.05, delays=0/0/0/0.04, dsn=2.0.0, status=sent (delivered via dovecot service)
Jul 19 07:59:11 mail postfix/qmgr[3224]: 96E1820C16: removed
答案2
除了 masegaloeh 的解释之外，我想指出的是，为什么垃圾邮件发送者已经成功了。查看日志中的以下行：
Jul 19 07:59:07 mail postfix/smtpd[15492]: NOQUEUE: reject_warning: RCPT from unknown[37.215.63.185]: 504 5.5.2 <37.215.63.185>: Helo command rejected: need fully-qualified hostname; from=<> to=<[email protected]> proto=SMTP helo=<37.215.63.185>
这已经是解决您的问题的说明，所以让我们看一下您的配置（请注意warn_if_reject：
smtpd_helo_restrictions = [...] warn_if_reject reject_non_fqdn_hostname, [...], permit
smtpd_sender_restrictions = [...], warn_if_reject reject_non_fqdn_sender, [...], permit
您的日志显示，该事件reject_non_fqdn_hostname已触发，但被阻止并转换为警告（您可以在日志中看到）。删除它，垃圾邮件发送者将被拒绝。
使用 时您不会丢失任何有效的发件人reject_non_fqdn_hostname，每个正确设置的邮件服务器都使用有效的 FQDN 进行 helo。
编辑：请考虑整理您的配置:) 您和其他人都可以在不需要每行三个注释掉的变体的配置中更好地定位自己。