GNU的mailutils里的mailx好像不太好使，所以这里使用s-nail。
¶ 安装
# ArchLinux
sudo pacman -S s-nail
# Debian
sudo apt install s-nail¶ ~/.mailrc
主要参考：https://wiki.archlinux.org/title/S-nail
# All the examples require v15-compat!
set v15-compat
# Essential setting: select allowed character sets
# (Have a look at the "Character sets" manual section)
set sendcharsets=utf-8,iso-8859-1
# A very kind option: when replying to a message, first try to
# use the same encoding that the original poster used herself!
set reply-in-same-charset
# When replying to or forwarding a message the comment and name
# parts of email addresses are removed unless this variable is set
set fullnames
# When sending messages, wait until the Mail-Transfer-Agent finishs.
set sendwait
# Only use builtin MIME types, no mime.types(5) files.
# That set is often sufficient, but look at the output of the
# `mimetype' command to ensure this is true for you, too
set mimetypes-load-control
# Default directory where we act in (relative to $HOME if not absolute)
set folder=mail
# A leading "+" (often) means: under folder
# record is used to save copies of sent messages, $DEAD is error storage
# inbox: system mailbox, by default /var/mail/$USER: file %
# $MBOX: secondary mailbox: file &
set MBOX=+mbox.mbox record=+sent.mbox DEAD=+dead.mbox
set inbox=+system.mbox
# It can be as easy as
# (Remember USER and PASS must be URL percent encoded)
set mta=smtp://用户名:授权码@smtp.163.com \
smtp-use-starttls
# It may be necessary to set hostname and/or smtp-hostname
# if the "SERVER" of smtp and "domain" of from do not match.
# Reading the "ON URL SYNTAX.." and smtp manual entries may be worthwhile
set from="用户名@163.com"mkdir ~/mail然后已发送的邮件就会存入~/mail/sent.mbox
Arch wiki里还设置了ssl-ca-file等变量，但我这里运行后会报这种错：
mail: Warning: variable superseded or obsoleted: ssl-ca-file
mail: Warning: variable superseded or obsoleted: ssl-ca-no-defaults
mail: Warning: variable superseded or obsoleted: ssl-protocol
mail: Warning: variable superseded or obsoleted: ssl-cipher-list
mail: Warning: variable superseded or obsoleted: ssl-verify所以我没有设置这些ssl相关的配置，实测也能跑。
¶ 发邮件
ArchLinux用mailx命令：
echo "test mailx" | mailx --subject="test" 接收人@163.comDebian用s-nail命令：
echo "test s-nail" | s-nail --subject="test" 接收人@163.com¶ 使用代理
云服务器商似乎会拦截SMTP协议的流量，aliyun和AWS上邮件都发不出去。走socks5代理给一台不存在此限制的服务器上即可：
echo "test s-nail" | s-nail -Ssocks-proxy=socks5://地址:端口号 --subject="test" 接收人@163.com¶ 相关
https://www.digitalocean.com/community/tutorials/send-email-linux-command-line