I have updated the Storage for Contact Form 7 plugin to keep the uploaded form files even when they are not sent in e-mail. It was a request from a user who wanted to avoid sending large files in e-mail and still have a reliable way of accessing them from the WordPress dashboard.
That’s a great feature. I know of people (unfortunately not using WordPress) who get too many large uploaded file for emailing them to be viable. Basically it chews through their email storage capacity allocation and starts rejecting emails. This would solve that problem.