(n1 {User} [ email: "alice@email.com" ])
// No email
(n2_wrong {User} [ name: "Bob" ])
// Wrong email without @
(n3_wrong {User} [ email: "carol" ])
// Email with an integer
(n4_wrong {User} [ email: 23 ])
// 2 emails
(n5_wrong {User} [ email: [ "email1@email.com", "email2@email.com" ] ])