我的 postfix+dovecot 邮件服务器一直有问题。每次我尝试将电子邮件发送到其他服务器（gmail 等）时，都会在日志中收到以下消息：
postfix/qmgr[28918]: warning: connect to transport private/smtp: Connection refused
postfix/error[29298]: BB36617ABFB: to=<[email protected]>, relay=none, delay=575, delays=575/0.01/0/0.01, dsn=4.3.0, status=deferred (mail transport unavailable)
不知何故，postfix 无法连接到其 postscreen 传输。这是我的 main.cf（已替换域）：
## These are all default Postfix settings that we won't change
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
append_dot_mydomain = no
biff = no
broken_sasl_auth_clients = yes
inet_protocols = ipv4, ipv6
inet_interfaces = all
mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/conf.d/99-mail-stack-delivery.conf -m "${EXTENSION}"
mailbox_size_limit = 0
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_path = private/dovecot-auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_type = dovecot
smtpd_tls_auth_only = yes
smtpd_tls_received_header = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
tls_random_source = dev:/dev/urandom
## Settings below this line are things we're modifying or adding
## Your mail server identity options
myhostname = domain1.com
mydestination = mail.domain1.com, localhost, mx.domain1.com
mynetworks = 127.0.0.0/8 10.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 172.17.0.0/16
## Customized smtpd paramters
smtpd_banner = $myhostname ESMTP
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks, reject_non_fqdn_helo_hostname, reject_invalid_helo_hostname, reject_unknown_helo_hostname, permit
smtpd_recipient_restrictions = permit_mynetworks, reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_sasl_authenticated, reject_unauth_destination, reject_invalid_hostname, reject_non_fqdn_sender
smtpd_sender_restrictions = permit_mynetworks, reject_unknown_sender_domain, reject_sender_login_mismatch
smtpd_sender_login_maps = $virtual_mailbox_maps
## Dealing with rejection: use permanent 550 errors to stop retries
unknown_address_reject_code = 550
unknown_hostname_reject_code = 550
unknown_client_reject_code = 550
## customized TLS parameters
smtpd_tls_ask_ccert = yes
smtpd_tls_cert_file = somewhere.crt
smtpd_tls_key_file = somewhere.key
smtpd_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtpd_tls_ciphers = high
smtpd_tls_loglevel = 1
smtpd_tls_security_level = may
smtpd_tls_session_cache_timeout = 3600s
## Customized Dovecot and virtual user-specific settings
canonical_maps = hash:/etc/postfix/canonical
home_mailbox = Maildir/
message_size_limit = 104857600
virtual_alias_maps = hash:/etc/postfix/virtual
virtual_alias_domains = hash:/etc/postfix/virtual-mailbox-domains
virtual_mailbox_maps = hash:/etc/postfix/virtual-mailbox-users
virtual_transport = dovecot
## This setting will generate an error if you restart Postfix before
## adding the appropriate service definition in master.cf, so make
## sure to get that taken care of!
dovecot_destination_recipient_limit = 1
## Customized milter settings
milter_default_action = accept
milter_connect_macros = j {daemon_name} v {if_name} _
non_smtpd_milters = $smtpd_milters
smtpd_milters = unix:/var/spool/postfix/spamass/spamass.sock unix:/var/spool/postfix/opendkim/opendkim.sock
## Other customized mail server settings
default_destination_concurrency_limit = 5
disable_vrfy_command = yes
relay_destination_concurrency_limit = 1
smtp_tls_note_starttls_offer = yes
smtp_tls_security_level = may
postscreen_greet_action = enforce
postscreen_dnsbl_action = enforce
postscreen_access_list = permit_mynetworks
postscreen_dnsbl_sites = zen.spamhaus.org, b.barracudacentral.org, bl.spamcop.net
myorigin = $myhostname
我的master.cf：
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (no) (never) (100)
# ==========================================================================
smtp inet n - n - 1 postscreen
smtpd pass - - n - - smtpd
dnsblog unix - - n - 0 dnsblog
tlsproxy unix - - n - 0 tlsproxy
submission inet n - n - - smtpd
-o syslog_name=postfix/submission
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-o milter_macro_daemon_name=ORIGINATING
pickup unix n - n 60 1 pickup
cleanup unix n - n - 0 cleanup
qmgr unix n - n 300 1 qmgr
tlsmgr unix - - n 1000? 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
proxywrite unix - - n - 1 proxymap
relay unix - - n - - smtp
showq unix n - n - - showq
error unix - - n - - error
retry unix - - n - - error
discard unix - - n - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - n - - lmtp
anvil unix - - n - 1 anvil
scache unix - - n - 1 scache
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/local/bin/maildrop -d ${recipient}
dovecot unix - n n - - pipe
flags=DRhu user=mail:mail argv=/usr/lib/dovecot/deliver
-f ${sender} -d ${user}@${nexthop} -a ${recipient}
虚拟邮箱域名：
domain1.com OK
domain2.net OK
我的服务器也在运行 IPv6，但不确定这是否与任何事情有关。如果您需要更多信息，请发表评论 ;)
提前致谢。
答案1
事实证明，
smtp unix - - n - - smtp
我注释掉了它，因为我收到了来自 postmap 的重复警告。我把它放回去后它就开始工作了。
答案2
我有同样的问题。
- postmap 发出警告：postmap：警告：master.cf.db：重复条目：“smtp”
- 无法向外部电子邮件地址发送邮件
我评论了这一行smtp unix - - n - - smtp因为那个。
删除评论即可解决问题。