http://www.example.com/index.php?option=com_acysms&ctrl=deliveryreport&gateway=telerivet&pass=S6fd65thisisafakepasswordstring

RewriteEngine On

RewriteCond %{HTTP_HOST} !^www.
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# force https:// for all except some selected URLs
RewriteCond %{HTTPS} off
RewriteCond %{THE_REQUEST} !/index.php?option=com_acysms&ctrl=deliveryreport&gateway=telerivet&pass=S6fd65thisisafakepasswordstring/ [NC]
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# force http:// for selected URLs
RewriteCond %{HTTPS} on
RewriteCond %{THE_REQUEST} /index.php?option=com_acysms&ctrl=deliveryreport&gateway=telerivet&pass=S6fd65thisisafakepasswordstring/ [NC]
RewriteRule ^ http://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]