1. 创建 sendmail证书
cd /etc/ssl/certs/
make sendmail.pem

2 .添加authinfo
在/etc/mail/access 中添加
AuthInfo:smtp.gmail.com “U:root” “I:User@gmail.com” “P:password” “M:PLAIN”
AuthInfo:smtp.gmail.com:587 “U:root” “I:User@gmail.com” “P:password” “M:PLAIN”
生成数据库
makemap -r hash /etc/mail/access.db < /etc/mail/access

3.配置smarthost
编辑 /etc/mail/sendmail.mc
在MAILER前添加
FEATURE(`authinfo',`hash /etc/mail/access.db')dnl
define(`SMART_HOST',`smtp.gmail.com')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')
define(`ESMTP_MAILER_ARGS', `TCP $h 587')
define(`CERT_DIR', `/etc/ssl/certs')
define(`confCACERT_PATH', `CERT_DIR')
define(`confCACERT', `CERT_DIR/ca-bundle.crt')
define(`confCRL', `CERT_DIR/ca-bundle.crt')
define(`confSERVER_CERT', `CERT_DIR/sendmail.pem')
define(`confSERVER_KEY', `CERT_DIR/sendmail.pem')
define(`confCLIENT_CERT', `CERT_DIR/sendmail.pem')
define(`confCLIENT_KEY', `CERT_DIR/sendmail.pem')
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')
写入到sendmail.cf中
m4 sendmail.mc > sendmail.cf

4.重启sendmail服务