已解决问题，是因为chrome浏览器下面ssl证书的问题，貌似自动生成的证书chrome浏览器不认，导致无法跳转。

解决办法：安装完成重启服务器以后，进行证书的统一设置，我使用的是免费的Let's Encrypt证书，好处是下次更新证书时，postfix/Dovecot/nginx  不需要重新设置，并会一起更新。

/etc/letsencrypt/live/<domain>/    这个目录是Let's Encrypt生成证书保存的目录。

yum install git
systemctl stop nginx

git clone https://github.com/certbot/certbot.git
./certbot-auto certonly --standalone --email support@<domain>   -d <domain>

postfix设置

postconf -e smtpd_tls_cert_file='/etc/letsencrypt/live/<domain>/cert.pem'
postconf -e smtpd_tls_key_file='/etc/letsencrypt/live<domain>/privkey.pem'
postconf -e smtpd_tls_CAfile='/etc/letsencrypt/live/<domain>/fullchain.pem'

Dovecot设置 vi  /etc/dovecot/dovecot.conf

ssl = required
verbose_ssl = no
#ssl_ca = </path/to/ca
#ssl_cert = </etc/pki/tls/certs/iRedMail.crt
#ssl_key = </etc/pki/tls/private/iRedMail.key

ssl_cert = </etc/letsencrypt/live/<domain>/cert.pem
ssl_key = </etc/letsencrypt/live/<domain>/privkey.pem
ssl_ca = </etc/letsencrypt/live/<domain>/fullchain.pem

nginx设置：vi /etc/nginx/templates/ssl.tmpl

ssl_certificate /etc/letsencrypt/live/<domain>/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/<domain>/privkey.pem;

重启服务：
systemctl  restart postfix
systemctl  restart dovecot
systemctl  restart nginx