https://www.jianshu.com/p/e25cd6b97b36
vim /etc/mail.rc
set from=noreply@cnbmxinyun.com
set smtp=smtps://smtp.cnbmxinyun.com:465
set smtp-auth=login
set smtp-auth-user=noreply@cnbmxinyun.com
set smtp-auth-password=123@Cnbmtech
set ssl-verify=ignore
set nss-config-dir=/etc/pki/nssdb/
$ echo -n | openssl s_client -connect smtp.cnbmxinyun.com:465 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /etc/pki/nssdb/xinyun.crt
$ certutil -A -n "GeoTrust SSL CA" -t "C,," -d /etc/pki/nssdb/ -i /etc/pki/nssdb/xinyun.crt
$ certutil -A -n "GeoTrust Global CA" -t "C,," -d /etc/pki/nssdb/ -i /etc/pki/nssdb/xinyun.crt
$ certutil -L -d /etc/pki/nssdb/