Contact Form 7 Customfield in mail plugin by Jeffrey van der Heide adds customfields in the mail section of Contact Form 7, by providing a new special mail tag.
Possible uses include:
Use the same contact form in different posts/pages
Send custom field values in the email
After installing and activating the plugin, you should use it like the following:
Double underscores are key!
The plug in recognizes a new special mail tag: [_customfield]
The tag alone doesn’t work though! You need to add two underscores after the tag: [_customfield__]
After this you can enter your custom field key i.e.: [_customfield__fieldName]
Downlaod and info: http://wordpress.org/extend/plugins/contact-form-7-customfield-in-mail/