mdoff

It’s not a standalone plugin requires installed Contact Form 7
This plugin solves problem of e.g. email verification or email confirmation.
Just create second field with <code>_confirm</code> at the end of the field name. Look in the screenshots for example.

cf7 Confirm Field

Plugin allows to make sure that e.g. emails in two fields are the same

Ryan Nevius

An add-on for Contact Form 7 (CF7) that provides a straightforward method to redirect visitors to success pages or thank you pages, if their messages are successfully delivered. If no message is sent, or if there is an error with the form, the user will not be redirected.
NOTE: This plugin requires Contact Form 7 version 3.9 or later.

Contact Form 7 – Success Page Redirects

An add-on for Contact Form 7 that provides a straightforward method to redirect visitors to success pages or thank you pages.

cf7 Confirm Field vs Contact Form 7 – Success Page Redirects