sudo tail /var/log/maillog
Oct 3 06:39:28 instance-23 postfix/master[63679]: warning: process /usr/libexec/postfix/trivial-rewrite pid 64274 exit status 1
Oct 3 06:39:28 instance-23 postfix/master[63679]: warning: /usr/libexec/postfix/trivial-rewrite: bad command startup -- throttling
Oct 3 06:39:54 instance-23 postfix/qmgr[63681]: warning: problem talking to service rewrite: Connection timed out
Oct 3 06:40:25 instance-23 postfix/postscreen[64336]: fatal: myhostname and relayhost parameter settings must not be identical: mail.duchi.net
Oct 3 06:40:26 instance-23 postfix/master[63679]: warning: process /usr/libexec/postfix/postscreen pid 64336 exit status 1
Oct 3 06:40:26 instance-23 postfix/master[63679]: warning: /usr/libexec/postfix/postscreen: bad command startup -- throttling
Oct 3 06:40:28 instance-23 postfix/trivial-rewrite[64337]: fatal: myhostname and relayhost parameter settings must not be identical: mail.duchi.net
Oct 3 06:40:29 instance-23 postfix/master[63679]: warning: process /usr/libexec/postfix/trivial-rewrite pid 64337 exit status 1
Oct 3 06:40:29 instance-23 postfix/master[63679]: warning: /usr/libexec/postfix/trivial-rewrite: bad command startup -- throttling
Oct 3 06:40:55 instance-23 postfix/qmgr[63681]: warning: problem talking to service rewrite: Connection timed out
答案1
邮件服务器或邮件传输代理（mta）所需的防火墙配置如下；
- SMTP 为 25、465、587
- 110, 995（POP）
- IMAP 为 143, 993
- 53 用于 DNS，
您可以使用从互联网上找到的端口控制网页检查上述端口。
另外，如果您可以指定操作系统，我可以帮助您定义防火墙。