我要使用来自centos 7的mailX发送电子邮件，这是我正在使用的命令。
echo "This is the message body and contains the message" | mailx -v -r "email@abc.com" -s "This is the subject" -S smtp="mail.xyz.abc.com:543" -S smtp-use-starttls -S smtp-auth=login -S nss-config-dir=/etc/pki/nssdb -S smtp-auth-user="email@abc.com" -S smtp-auth-password="pwd" -S ssl-verify=ignore toEmail@abc.com
输出：
Resolving host mail.xyz.abc.com . . . done.
Connecting to 204.XX.XX.XX:smtp . . . connected.
220 ZDXPPM1.dx.XXX.com ESMTP Tue, 11 Dec 2018 08:12:36 -0600
>>> EHLO es-master.novalocal
250-ZDXPPM1.dx.deere.com Hello zdxltm.dx.deere.com [204.53.110.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250 8BITMIME
>>> STARTTLS
454 4.3.3 Unable to start TLS
smtp-server: 454 4.3.3 Unable to start TLS
"/root/dead.letter" 11/375
. . . message not sent.
/etc/mail.rc文件：
set smtp=mail.xyz.abc.com
set smtp-auth-user=ds21746
set smtp-auth-password=turkey15
set smtp-auth=login