Apache http to https redirection
I wanted to force all users to use https://mymailserver.com instead of http://mymailserver.com.
Open apache config file ( httpd.conf or apache2.conf or sites-enabled/000-default ?? )
Add these lines
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*) https://%{SERVER_NAME}$1 [R,L]
/etc/init.d/apache2 restart