Contact Form 7 does not save submitted messages — it forwards them via e-mail. Issues can occur on the mail server or client side, and the mail is lost. You are no longer able to access that information. This is definitely a crisis situation.
You can cover this issue with another plugin, Flamingo.
Flamingo is my new plugin created to be a total CRM package for WordPress. Flamingo doesn’t currently have many features, but it can manage your contact list and submitted messages via contact forms.
To start managing messages with Flamingo, simply install and activate Flamingo. You don’t need any special configuration. Flamingo automatically cooperates with Contact Form 7 to store submitted messages. You can then view the messages in the Flamingo admin screen.