我可以接收邮件，但无法在 Squirrelmail 中发送到外界。
Message not sent. Server replied:
Temporary authentication failure
454 4.7.1 <[email protected]>: Relay access denied
我仔细检查了 postfix 是否正常工作，即能否通过 mail.domain.com 和 smtp.domain.com 进行 telnet。Dovecot 也能正常工作。看来 Squirrelmail 是个可疑对象。尝试配置，不确定是什么原因导致问题。
日志显示此信息：
mail.domain.com postfix/smtpd[4443]: connect from mail.domain.com[XXX.XXX.XXX.XXX]
mail.domain.com postfix/smtpd[4443]: NOQUEUE: reject: RCPT from mail.domain.com[XXX.XXX.XXX.XXX]: 454 4.7.1 <[email protected]>: Relay access denied; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<mail.domain.com>
mail.domain.com postfix/smtpd[4443]: lost connection after RCPT from mail.domain.com[XXX.XXX.XXX.XXX]
mail.domain.com postfix/smtpd[4443]: disconnect from mail.domain.com[XXX.XXX.XXX.XXX] ehlo=1 mail=1 rcpt=0/1 commands=2/3
网络状态监测
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:110 0.0.0.0:* LISTEN 940/dovecot
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN 940/dovecot
tcp 0 0 192.168.124.1:53 0.0.0.0:* LISTEN 1107/dnsmasq
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1905/cupsd
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 937/master
tcp 0 0 0.0.0.0:993 0.0.0.0:* LISTEN 940/dovecot
tcp 0 0 0.0.0.0:995 0.0.0.0:* LISTEN 940/dovecot
tcp6 0 0 :::110 :::* LISTEN 940/dovecot
tcp6 0 0 :::143 :::* LISTEN 940/dovecot
tcp6 0 0 :::80 :::* LISTEN 3521/httpd
tcp6 0 0 ::1:631 :::* LISTEN 1905/cupsd
tcp6 0 0 :::993 :::* LISTEN 940/dovecot
tcp6 0 0 :::995 :::* LISTEN 940/dovecot
udp 0 0 127.0.0.1:323 0.0.0.0:* 736/chronyd
udp 0 0 0.0.0.0:5353 0.0.0.0:* 722/avahi-daemon: r
udp 0 0 0.0.0.0:55024 0.0.0.0:* 722/avahi-daemon: r
udp 0 0 192.168.124.1:53 0.0.0.0:* 1107/dnsmasq
udp 0 0 0.0.0.0:67 0.0.0.0:* 1107/dnsmasq
udp6 0 0 :::41119 :::* 722/avahi-daemon: r
udp6 0 0 ::1:323 :::* 736/chronyd
udp6 0 0 :::5353 :::* 722/avahi-daemon: r
Iptables如下：
iptables -S
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A INPUT -i virbr0 -p udp -m udp --dport 53 -j ACCEPT
-A INPUT -i virbr0 -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -i virbr0 -p udp -m udp --dport 67 -j ACCEPT
-A INPUT -i virbr0 -p tcp -m tcp --dport 67 -j ACCEPT
-A FORWARD -d 192.168.124.0/24 -o virbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -s 192.168.124.0/24 -i virbr0 -j ACCEPT
-A FORWARD -i virbr0 -o virbr0 -j ACCEPT
-A FORWARD -o virbr0 -j REJECT --reject-with icmp-port-unreachable
-A FORWARD -i virbr0 -j REJECT --reject-with icmp-port-unreachable
-A OUTPUT -o virbr0 -p udp -m udp --dport 68 -j ACCEPT
iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:bootps
ACCEPT tcp -- anywhere anywhere tcp dpt:bootps
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere 192.168.124.0/24 ctstate RELATED,ESTABLISHED
ACCEPT all -- 192.168.124.0/24 anywhere
ACCEPT all -- anywhere anywhere
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:bootpc
iptables-保存
*mangle
:PREROUTING ACCEPT [9985:4365661]
:INPUT ACCEPT [9969:4364853]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [10509:2272775]
:POSTROUTING ACCEPT [10545:2275457]
-A POSTROUTING -o virbr0 -p udp -m udp --dport 68 -j CHECKSUM --checksum-fill
COMMIT
*nat
:PREROUTING ACCEPT [78:6056]
:INPUT ACCEPT [62:5248]
:OUTPUT ACCEPT [1057:68220]
:POSTROUTING ACCEPT [1057:68220]
-A POSTROUTING -s 192.168.124.0/24 -d 224.0.0.0/24 -j RETURN
-A POSTROUTING -s 192.168.124.0/24 -d 255.255.255.255/32 -j RETURN
-A POSTROUTING -s 192.168.124.0/24 ! -d 192.168.124.0/24 -p tcp -j MASQUERADE --to-ports 1024-65535
-A POSTROUTING -s 192.168.124.0/24 ! -d 192.168.124.0/24 -p udp -j MASQUERADE --to-ports 1024-65535
-A POSTROUTING -s 192.168.124.0/24 ! -d 192.168.124.0/24 -j MASQUERADE
COMMIT
*filter
:INPUT ACCEPT [9969:4364853]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [10509:2272775]
-A INPUT -i virbr0 -p udp -m udp --dport 53 -j ACCEPT
-A INPUT -i virbr0 -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -i virbr0 -p udp -m udp --dport 67 -j ACCEPT
-A INPUT -i virbr0 -p tcp -m tcp --dport 67 -j ACCEPT
-A FORWARD -d 192.168.124.0/24 -o virbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -s 192.168.124.0/24 -i virbr0 -j ACCEPT
-A FORWARD -i virbr0 -o virbr0 -j ACCEPT
-A FORWARD -o virbr0 -j REJECT --reject-with icmp-port-unreachable
-A FORWARD -i virbr0 -j REJECT --reject-with icmp-port-unreachable
-A OUTPUT -o virbr0 -p udp -m udp --dport 68 -j ACCEPT
COMMIT
2017 年 11 月 15 日更新：通过更改 Squirrelmail 中的配置，此问题已得到解决。运行
/usr/share/squirrelmail/config/conf.pl
转到：服务器设置 -> 更新 IMAP 设置 -> imap.domain.com 和更新 SMTP 设置 -> smtp.domain.com。它以前只是 localhost。
更新 14.11.2017：禁用防火墙后，可以再次发送邮件。但是，iptables 的问题仍然存在。在 SELinux 中，我还尝试了：
setsebool -P httpd_can_network_connect 1
更新 2017 年 11 月 13 日 启用防火墙并打开端口 80/443、25/143 后无法在 Squirrelmail 上发送电子邮件。请帮忙！
错误：消息未发送。服务器回复：
Connection refused
111 Can't open SMTP stream.
该问题来自以下帖子。 Postfix、dovecot、squirrelmail 服务器可以发送但不能接收邮件
答案1
我终于能够通过编辑 Squirrelamil 配置文件来发送电子邮件。基本上，我从 SMTP 切换到 Sendmail。在 /etc/squirrelmail/config.php 中更改
$useSendmail = true;
然后重新启动 apache
systemctl restart httpd
然后允许 Selinux 使用 sendmail
setsebool -P httpd_can_sendmail=1
我怀疑 Squirrelmail 的这种配置能否维持很长时间。我肯定会尝试一下。目前，我不确定为什么 SMTP 不起作用，而 sendmail 却起作用。希望能够通过摆弄 SELinux 来找出答案。与此同时，有人对 SMTP 或 Sendmail 哪个最好用有什么看法吗？