best contact form plugin across multisites


I've built an 8-site multisite network installation with your domain mapping plugin and I need to find a solid contact form plugin that functions in that kind of environment. I will need to make multiple contact forms (at least 1 per domain), allow users to upload files up to 20 MB and then deliver the form contents to another server on a different host, and allow the forms to be easily customizable for the 8 different website styles. Captcha and any other anti-spam measures are also a must.

Any ideas?