我正在尝试使用 Postfix 设置 SMTP 服务器。我已经有虚拟邮箱和 Dovecot IMAP 服务器正在运行（并且正常工作）。我可以使用 IMAP 客户端查看收到的邮件。但是，无法从外部位置发送邮件。mail [email protected]
我从内部执行了 netcat：
root@cs:/# netcat localhost 25
220 camilstaps.nl ESMTP Postfix (Ubuntu)
helo localhost
250 camilstaps.nl
mail from:<[email protected]>
250 2.1.0 Ok
rcpt to:<[email protected]>
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
Subject: Test
Hello
.
250 2.0.0 Ok: queued as 19CBA412F0
并且还尝试了来自外部服务器的 netcat，但是没有用，我没有得到响应（shell 保持打开状态直到我^C或发生超时）。
我认为服务器没有监听每个 IP，因此我尝试了 netstat，结果如下：
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 2378/master
tcp6 0 0 :::25 :::* LISTEN 2378/master
所以这不是问题所在，对吧？但我不明白问题是什么。
这是/etc/postfix/master.cf（它太长了所以我删除了评论）：
smtp inet n - - - - smtpd
pickup unix n - - 60 1 pickup
cleanup unix n - - - 0 cleanup
qmgr unix n - n 300 1 qmgr
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}
并postconf -n给出：
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
broken_sasl_auth_clients = yes
config_directory = /etc/postfix
home_mailbox = Maildir/
inet_interfaces = all
inet_protocols = all
mailbox_command =
mailbox_size_limit = 0
mydestination = $myhostname, localhost.$mydomain, $mydomain, localhost
myhostname = camilstaps.nl
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_note_starttls_offer = yes
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_client_restrictions = permit_mynetworks permit_inet_interfaces permit_sasl_authenticated permit_tls_clientcerts reject_unauth_destination
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
smtpd_sasl_path = private/auth-client
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_tls_CAfile = /etc/ssl/certs/cacert.pem
smtpd_tls_auth_only = no
smtpd_tls_cert_file = /etc/ssl/certs/smtpd.crt
smtpd_tls_key_file = /etc/ssl/private/smtpd.key
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_tls_session_cache_timeout = 3600s
smtpd_use_tls = yes
tls_random_source = dev:/dev/urandom
virtual_gid_maps = static:5000
virtual_mailbox_base = /home/vmail/
virtual_mailbox_domains = /etc/postfix/vhosts
virtual_mailbox_maps = hash:/etc/postfix/vmaps
virtual_minimum_uid = 1000
virtual_uid_maps = static:5000
答案1
问题原来是我的 ISP 阻止了端口 25。
我从另一台未被阻止的服务器上进行了测试，并且它可以正常工作。