proxy problem

[lucas at landm.net]

 Hi,

   We had nginx/0.6.33 and we migrated to nginx/0.7.65.
We use nginx as frontend for our webmail, that it is in another machine
(nginx+apache).
But in the new scenario, squirrelmail loss session (I guess) and force me
to relogin again.
Compile options and config files are the same (except for proxy_redirect)

This is:
        location / {
                proxy_pass http://mailmachine:80;
                proxy_redirect     default;  // for nginx 0.7.65
                proxy_redirect     on; // for nginx 0.6.33

                proxy_set_header   Host             $host;
                proxy_set_header   X-Real-IP        $remote_addr;
                proxy_set_header   X-Forwarded-For 
$proxy_add_x_forwarded_for;
                proxy_set_header   X-Forwarded-Proto https;
                client_max_body_size       10m;
                client_body_buffer_size    128k;
                proxy_connect_timeout      90;
                proxy_send_timeout         90;
                proxy_read_timeout         90;
                proxy_buffering            on;
                proxy_buffers              8 8k;
                proxy_buffer_size          8k;
                proxy_busy_buffers_size    16k;
                proxy_temp_file_write_size 1024m;
        }

 What changes are in version 0.7 that I should consider?

 Thank you in advance,
    Lucas