运行 devuan、mutt 和 exim4。不知什么原因，发送邮件失败。
我给自己发了一条信息
$ echo "test" | mail -s Testing [email protected]
尽管我认为邮件是与 sendmail 而不是 exim 通信，但 exim 日志中却是这样的：
2019-06-04 02:57:13 1hY3Nh-0007fn-3o <= [email protected]
U=haines P=local S=409
2019-06-04 02:57:13 1hY3Nh-0007fn-3o ** [email protected]
R=smarthost T=remote_smtp_smarthost
H=mail.historicalmaterialism.info
[216.239.133.246]: SMTP error from remote mail server after pipelined
MAIL FROM:<[email protected]> SIZE=1444: 550 5.7.1
<unknown[32.210.114.254]>: Client host rejected: Authentication
failed, please enable SMTP Authentication in your email client
2019-06-04 02:57:13 1hY3Nh-0007fq-S4 <= <> R=1hY3Nh-0007fn-3o
U=Debian-exim P=local S=2145
2019-06-04 02:57:13 1hY3Nh-0007fn-3o Completed
2019-06-04 02:57:14 1hY3Nh-0007fq-S4 => haines
<[email protected]> R=local_user T=mail_spool
2019-06-04 02:57:14 1hY3Nh-0007fq-S4 Completed
如果我发送到其他地址或者由其他用户、root 或另一个磁盘上的操作系统上的用户发送，也会出现同样的问题。
# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
目标 保护 优化 源 目标
在 /etc/exim4/passwd.client 中我有：
*:[email protected]:<pw>
*:[email protected]:<pw>
*:[email protected]:<pw>