I've installed nginx and run site success.but now,i wish reconfigure nginx with same configure before and add send mail command.

[code]
sudo ./configure --sbin-path=/usr/local/sbin --with-http_stub_status_module --with-http_flv_module --with-http_ssl_module --with-http_gzip_static_module --with-http_realip_module --without-mail_pop3_module --without-mail_imap_module --without-mail_smtp_module --add-module=../masterzen-nginx-upload-progress-module/ --add-module=../nginx_upload_module-2.2.0/
[/code]

So if i reconfigure,should backup config before?and what configure i do now?
Thanks.