Contact Form 7 – Not Taking custom field value of the respective post

I have 5 posts which is in same category displayed in a page which have a custom field called “email”. I want to set this field as “To” field . I refered the following link and came to a solution.
http://sevenspark.com/wordpress-plugins/how-to-dynamically-set-the-recipient-to-email-address-in-contact-form-7

But In this it is not taking custom field values according to the post. It takes it in ascending order. Following is what i did to get the custom field value.

[dynamichidden dynamichidden-836 "CF7_get_custom_field key='email'"].

What should I do to get the correct custom field value according to the post??

http://wordpress.org/plugins/contact-form-7/