我遇到了反向散射问题。垃圾邮件发送者向我服务器上托管的不存在的用户名@存在的域发送电子邮件。我试图中止会话，而不是将退回邮件发送回伪造的发件人地址。我尝试添加reject_unverified_recipient，但似乎不起作用。
当我检查 mailq 时，我可以看到许多卡住的“用户不存在”电子邮件从 MAILER_DAEMON 退回到不存在的收件人。
这是我的 postconf -n
append_dot_mydomain = no
biff = no
broken_sasl_auth_clients = yes
config_directory = /etc/postfix
dovecot_destination_recipient_limit = 1
inet_interfaces = all
inet_protocols = ipv4
mailbox_size_limit = 0
message_size_limit = 102400000
milter_default_action = accept
milter_protocol = 2
mydestination = localhost
myhostname = domain.com
mynetworks = 127.0.0.0/8
non_smtpd_milters = inet:localhost:8891
readme_directory = no
recipient_delimiter = +
relay_domains =
relayhost =
resolve_numeric_domain = yes
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_milters = inet:localhost:8891
smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_unknown_recipient_domain, reject_unverified_recipient, permit_auth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_tls_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_tls_CAfile = /etc/ssl/certs/domain.com.chain.crt
smtpd_tls_cert_file = /etc/ssl/certs/domain.com.crt
smtpd_tls_key_file = /etc/ssl/private/domain.com.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
virtual_alias_domains = mysql:/etc/postfix/sqlconf/virtual_alias_domains.cf
virtual_alias_maps = mysql:/etc/postfix/sqlconf/virtual_mailbox_maps.cf
virtual_mailbox_domains = mysql:/etc/postfix/sqlconf/mydestination.cf
virtual_transport = dovecot
这是 master.cf 文件
smtp inet n - - - - smtpd
-o content_filter=spamassassin
-o receive_override_options=no_header_body_checks,no_unknown_recipient_checks,no_milters
smtps inet n - - - - smtpd
-o content_filter=checkhook
-o smtpd_tls_wrappermode=yes
-o smtpd_sasl_auth_enable=yes
dovecot unix - n n - - pipe
flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${recipient}
pickup unix n - - 60 1 pickup
cleanup unix n - - - 0 cleanup
qmgr unix n - n 300 1 qmgr
#qmgr unix 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
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
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$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=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}
spamassassin unix - n n - - pipe
user=spamfilter argv=/usr/bin/spamc -f -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}
checkhook unix - n n - - pipe
user=www-data argv=/etc/postfix/scripts/send ${sender} ${recipient}
以下是我尝试发送给无效的本地收件人时生成的一些日志。
Jan 22 19:09:34 ip-12345 postfix/qmgr[19938]: CF96B20013B: from=<[email protected]>, size=249, nrcpt=1 (queue active)
Jan 22 19:09:35 ip-12345 postfix/pickup[19939]: 982D320013D: uid=5007 from=<[email protected]>
Jan 22 19:09:35 ip-12345 postfix/pipe[21485]: CF96B20013B: to=<[email protected]>, relay=spamassassin, delay=18, delays=16/0/0/1.2, dsn=2.0.0, status=sent (delivered via spamassassin service)
Jan 22 19:09:35 ip-12345 postfix/qmgr[19938]: CF96B20013B: removed
Jan 22 19:09:35 ip-12345 postfix/cleanup[21477]: 982D320013D: message-id=<[email protected]>
Jan 22 19:09:35 ip-12345 postfix/qmgr[19938]: 982D320013D: from=<[email protected]>, size=1333, nrcpt=1 (queue active)
Jan 22 19:09:35 ip-12345 dovecot: auth: Debug: master in: USER#0111#[email protected]#011service=lda
Jan 22 19:09:35 ip-12345 dovecot: auth-worker(14636): Debug: sql([email protected]): SELECT '/var/vmail/[email protected]' as home, 'vmail' as uid, 'vmail' as gid, concat('*:storage=', quota_kb) AS quota_rule, concat('*:messages=', quota_msg) AS quota_rule2 FROM users WHERE username = 'nonexistentx' AND domain = 'localdomain.com' and active=1
Jan 22 19:09:35 ip-12345 dovecot: auth-worker(14636): sql([email protected]): unknown user
Jan 22 19:09:35 ip-12345 dovecot: auth: Debug: userdb out: NOTFOUND#0111
Jan 22 19:09:35 ip-12345 postfix/pipe[21400]: 982D320013D: to=<[email protected]>, relay=dovecot, delay=0.07, delays=0.05/0/0/0.02, dsn=5.1.1, status=bounced (user unknown)
Jan 22 19:09:35 ip-12345 postfix/cleanup[21396]: A8B0720013C: message-id=<[email protected]>
Jan 22 19:09:35 ip-12345 postfix/bounce[21474]: 982D320013D: sender non-delivery notification: A8B0720013C
Jan 22 19:09:35 ip-12345 postfix/qmgr[19938]: A8B0720013C: from=<>, size=3394, nrcpt=1 (queue active)
Jan 22 19:09:35 ip-12345 postfix/qmgr[19938]: 982D320013D: removed
Jan 22 19:09:35 ip-12345 postfix/smtp[21496]: A8B0720013C: to=<[email protected]>, relay=none, delay=0.03, delays=0/0.01/0.02/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=sender.ocm type=A: Host not found)
Jan 22 19:09:35 ip-12345 postfix/qmgr[19938]: A8B0720013C: removed
答案1
也许你可以从Postfix 反向散射方法。
如果你真的想摆脱持续的反向散射/垃圾邮件发送者，你可能需要实施失败2ban政策结合后筛选。Postscreen 本身可以消除几乎所有的垃圾邮件发送者，并且只占用很少的资源，而且它非常容易实现，因为它已经是 postfix 的一部分。
答案2
您可以在 master.cf 中禁用反弹
bounce unix - - - - 0 discard
或者配置 spf 检查（perl 和 python 或 amavis/spamassassin 中有模块）以丢弃未通过 spf 检查的消息，并且不会对非法来源生成退回，但仍然能够通知合法邮件来源（满配额、消息大小超出限制、不再使用的旧地址等）