Solution

Here’s why…

There are many ways to prompt the user to re-enter their email address, but the “best choice” depends on the tone that the company wants to set.

The tone here is casual, and the message tells the user exactly what’s wrong.

Most of the time when a user enters the wrong email address, it’s because they either mistyped it, or they are using an address associated with another app. In any case, it’s a common mistake, so it’s best to keep the tone casual and easy going.

“Hmm…” makes the message more human and relatable, since that’s what a person might actually say. “We don’t recognize this email” lets the user know exactly what’s wrong, and what they need to do to correct the problem. “Let’s try that again” prompts the user to re-enter their email, while also implying that the app is working with them to help them sign in.