我已经在 VPS 上设置了 postfix，以便可以发送/接收电子邮件。通过 SquirrelMail 访问电子邮件很方便 - 我可以发送和接收电子邮件。但是，使用电子邮件客户端 (Thunderbird) 我可以正常接收电子邮件，但在尝试发送电子邮件时会收到以下错误消息：
Sending of message failed.
The message could not be sent because the connection to SMTP server [server] timed out. Try again or contact your network administrator.
我在这里和其他论坛上查看过类似的问题，但这些建议对我都不起作用。我真的不知道需要什么信息，所以在下面包含了各种信息，但如果您需要其他信息，我可以尝试提供！
尾部/var/log/maillog：
Aug 23 22:59:05 redsquirsoft postfix/smtpd[15406]: connect from cpc2-telf10-2-0-cust377.wolv.cable.virginmedia.com[my.ip.add.ress]
Aug 23 23:00:50 redsquirsoft postfix/smtpd[14820]: lost connection after UNKNOWN from cpc2-telf10-2-0-cust377.wolv.cable.virginmedia.com[my.ip.add.ress]
Aug 23 23:00:50 redsquirsoft postfix/smtpd[14820]: disconnect from cpc2-telf10-2-0-cust377.wolv.cable.virginmedia.com[my.ip.add.ress]
telnet mydomain.com 25：
Connected to mydomain.com.
Escape character is '^]'.
220 vpshostingdomain.com ESMTP Postfix
ehlo mydomain.com
250-vpshostingdomain.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: <[email protected]>
250 2.1.0 Ok
/etc/postfix/main.cf：
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
mydomain = mydomain.com
myorigin = $mydomain
inet_interfaces = all
inet_protocols = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
debug_peer_level = 2
debugger_command =
PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
ddd $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.6.6/samples
readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES
smtpd_sasl_local_domain = $mydomain
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination
mynetworks = 127.0.0.0/8
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
home_mailbox = Maildir/
mailbox_command =
smtpd_tls_security_level = may
smtpd_tls_key_file = my .key file
smtpd_tls_cert_file = my .crt file
smtpd_tls_loglevel = 1
smtpd_tls_session_cache_timeout = 3600s
smtpd_tls_session_cache_database = btree:/var/spool/postfix/smtpd_tls_cache
tls_random_source = dev:/dev/urandom
smtpd_tls_auth_only = yes
smtpd_relay_restrictions = permit_sasl_authenticated
/etc/sasl2/smtpd.conf：
pwcheck_method: saslauthd
mech_list: plain login
正如我所说的，我真的不知道还需要什么其他信息，所以如果您还有其他需要，请告诉我，并提前感谢您的帮助！:)
更新 1
/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 - n - - smtpd
#submission inet n - n - - smtpd
# -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 - n - - smtpd
-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 - n - - qmqpd
pickup fifo n - n 60 1 pickup
cleanup unix n - n - 0 cleanup
qmgr fifo n - n 300 1 qmgr
#qmgr fifo n - n 300 1 oqmgr
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
smtp unix - - n - - smtp
# When relaying mail as backup MX, disable fallback_relay to avoid MX loops
relay unix - - n - - smtp
-o smtp_fallback_relay=
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
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
#
# ====================================================================
# 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/local/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# The Cyrus deliver program has changed incompatibly, multiple times.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -r ${sender} -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/local/sbin/bsmtp -f $sender $nexthop $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}
更新2
Wireshark：
...........R...}J.eO....U.\...,..9...y..X....H...
.......9.8.......5.........E.D.3.2...........A...../.........
.....
...=...#.!...mydomain.com.
.................#..220 vpshostingdomain.com ESMTP Postfix
502 5.5.2 Error: command not recognized
502 5.5.2 Error: command not recognized
502 5.5.2 Error: command not recognized
答案1
也许你的 ISP 阻止了 SMTP 连接？就像这个问题（第一个答案）：Postfix、SASL、MySQL 问题