我在 VPS 上安装了 Ubuntu 10.04，并为单个系统用户安装并设置了 Postfix 和 Dovecot，如下所示这和这指南。我可以发送电子邮件，但无法接收。我有一个域名 tema.ee，它具有所有必要的 DNS 记录
tema@artemis:~$ host tema.ee
tema.ee has address 46.182.27.240
tema.ee mail is handled by 10 tema.ee.
tema@artemis:~$ host -t NS tema.ee
tema.ee name server ns2.selectel.org.
tema.ee name server ns1.selectel.org.
/var/log/mail.log在我应该接收电子邮件时，除了 imap 登录和断开连接消息之外没有任何东西。
主机文件：
tema@artemis:~$ sudo cat /etc/hosts
127.0.0.1 localhost
46.182.27.240 tema.ee artemis
主机名：
tema@artemis:~$ hostname -f
tema.ee
Netstat 输出：
tema@artemis:~$ netstat -tap
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 *:imap2 *:* LISTEN -
tcp 0 0 *:sunrpc *:* LISTEN -
tcp 0 0 *:36243 *:* LISTEN -
tcp 0 0 *:ssh *:* LISTEN -
tcp 0 0 *:imaps *:* LISTEN -
tcp 0 0 *:2025 *:* LISTEN -
tcp 0 48 tema.ee:ssh 89-235-215-24.sat:62504 ESTABLISHED -
tcp 0 0 tema.ee:imaps 89-235-215-24.sat:63988 ESTABLISHED -
tcp 0 0 tema.ee:imaps 89-235-215-24.sat:63992 ESTABLISHED -
tcp6 0 0 [::]:ssh [::]:* LISTEN -
tcp6 0 0 [::]:2025 [::]:* LISTEN -
这是我的main.cf后缀：
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
append_dot_mydomain = no
#delay_warning_time = 4h
readme_directory = no
# TLS parameters
smtpd_tls_cert_file = /etc/ssl/certs/smtpd.crt
smtpd_tls_key_file = /etc/ssl/private/smtpd.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
myhostname = tema.ee
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = tema.ee, localhost, artemis
relayhost =
mynetworks = 127.0.0.0/8 # [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
home_mailbox = Maildir/
mailbox_command =
smtpd_sasl_local_domain =
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtp_tls_security_level = may
smtpd_tls_security_level = may
smtpd_tls_auth_only = no
smtp_tls_note_starttls_offer = yes
smtpd_tls_CAfile = /etc/ssl/certs/cacert.pem
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
实际上，一开始我以为是 DNS 的问题，但我已经设置了第二个虚拟机，使用了另一个域名（来自不同的注册商），进行了相同的配置，结果相同 — 我可以发送邮件，但无法接收邮件。问题可能出在哪里？
答案1
存在防火墙问题。
您的主机在端口 25 上不可用
% nc 46.182.27.240 25
(UNKNOWN) [46.182.27.240] 25 (smtp) : No route to host
查看（或向我们展示）的输出
iptables-save