APACHE - Redirect http requests to https

First make sure Apache is configured for HTTPS connection and necessary SSL certificates are installed.

No non-ssl access i.e. only accept https connections

Now open httpd.conf or .htaccess file (mod_rewrite not required):
# vi httpd.conf

Append following line :
Redirect permanent / https://mail.nixcraft.com/

Any request made to http://mail.nixcraft.com will goto https://mail.nixcraft.com/

Save and close the file. Restart the Apache:
# systemctl restart httpd