今天研究实现了手动或者定时自动通过LEDE/openwrt路由对外发送邮件的功能。
1.安装软件包。

opkg update
opkg install mutt ssmtp ca-certificates ca-bundle

2.配置ssmtp

vi /etc/ssmtp/ssmtp.conf

内容为：

#
# /etc/ssmtp.conf -- a config file for sSMTP sendmail.
#

# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=MY@TEST.com

# The place where the mail goes. The actual machine name is required
# no MX records are consulted. Commonly mailhosts are named mail.domain.com
# The example will fit if you are in domain.com and your mailhub is so named.
# 不同邮箱供应商的配置不同，需查阅供应商手册
mailhub=smtp.TEST.com:465

# Example for SMTP port number 2525
# mailhub=mail.your.domain:2525
# Example for SMTP port number 25 (Standard/RFC)
# mailhub=mail.your.domain
# Example for SSL encrypted connection
# mailhub=mail.your.domain:465

# Where will the mail seem to come from?
rewriteDomain=TEST.com

# The full hostname
hostname=TEST.com

# Set this to never rewrite the "From:" line (unless not given) and to
# use that address in the "from line" of the envelope.
FromLineOverride=YES

# Use SSL/TLS to send secure messages to server.
UseTLS=YES

# Use SSL/TLS certificate to authenticate against smtp host.
#UseTLSCert=YES

# Use this RSA certificate.
#TLSCert=/etc/ssl/certs/ssmtp.pem

# Get enhanced (*really* enhanced) debugging information in the logs
# If you want to have debugging of the config file parsing, move this option
# to the top of the config file and uncomment
#Debug=YES

然后：

vi /etc/ssmtp/revaliases

内容为：

# sSMTP aliases
#
# Format:       local_account:outgoing_address:mailhub
#
# Example: root:your_login@your.domain:mailhub.your.domain[:port]
# where [:port] is an optional port number that defaults to 25.
root:MY@TEST.com:smtp.TEST.com:465

3.配置mutt

vi ~/.muttrc

内容为：

mailboxes /tmp/mail
set sendmail="ssmtp -v -auMY@TEST.com -apMYPASSWORD"
set from="MY@TEST.com"
# Mail folder setup.
set folder=/tmp/mail
set mbox_type=mbox
set spoolfile=+inbox
set mbox=+received
set postponed=+postponed
set record=+sent

4.编写脚本sendmail.sh

vi ./sendmail.sh
chmod +x ./sendmail.sh

内容为：

mkdir /tmp/mail
cat /tmp/sysinfo/model | mutt  -s "Mail from Router of Coffeecat"  receiver@TEST.com -a 'attachment.txt'

然后运行：
./sendmail.sh
就可以看到结果了（如果是从vip.qq.com发送的话）：

[<-] 220 smtp.qq.com Esmtp QQ Mail Server
[->] EHLO vip.qq.com
[<-] 250 8BITMIME
[->] AUTH LOGIN
[<-] 334 XXYlcm5hbDF6
[->] Z2FyACDDbTT4dBB2aXAucWSuY29t
[<-] 334 REWzc3dverH6
[<-] 235 Authentication successful
[->] MAIL FROM:<MY@TEST.com>
[<-] 250 Ok
[->] RCPT TO:<reciever@TEST.com>
[<-] 250 Ok
[->] DATA
[<-] 354 End data with <CR><LF>.<CR><LF>
[->] Received: by vip.qq.com (sSMTP sendmail emulation); Tue, 30 Jan 2018 22:25:31 +0800
[->] Date: Tue, 30 Jan 2018 22:25:31 +0800
[->] From: root <MY@TEST.com>
[->] To: reciever@TEST.com
[->] Subject: Mail from Router of Coffeecat
[->] Message-ID: <20180130142531.GA1968@Exciting.lan>
[->] MIME-Version: 1.0
[->] Content-Type: multipart/mixed; boundary="Nq2Wo0NMKNjxTN9z"
[->] Content-Disposition: inline
[->] User-Agent: Mutt/1.9.2 (2017-12-15)
[->]
[->]
[->] --Nq2Wo0NMKNjxTN9z
[->] Content-Type: text/plain; charset=us-ascii
[->] Content-Disposition: inline
[->]
[->] HiWiFi HC5962
[->]
[->] --Nq2Wo0NMKNjxTN9z
[->] Content-Type: text/plain; charset=us-ascii
[->] Content-Disposition: attachment; filename="maclist.txt"
[->] .......
[->]
[->] --Nq2Wo0NMKNjxTN9z--
[->] .
[<-] 250 Ok: queued as
[->] QUIT
[<-] 221 Bye