By default, the WordPress mailer (which CF7 used to send email) fills in the From: field with firstname.lastname@example.org and the From: name as WordPress.
CF7 replaces this with the info you enter in Mail section of the CF7 interface - provided you fill this in correctly and the plugin is working.
Sounds like you have some problem on your site.
Include all your input in both the Form section and Mail section of the CF7 interface and a link to your CF7 form if possible. If others here are able to understand your actual problem, they may be able and willing to offer a possible solution.