all model tests now pass

app/models/credential.rb

@@ -1,2 +1,5 @@
 class Credential < ApplicationRecord
+    validates :email, presence: true
+    validates :email, uniqueness: true
+    validates :email, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i , message: "email must be valid"}
 end

app/models/virtual.rb

@@ -2,6 +2,9 @@ class Virtual < ApplicationRecord
     validate :domain_name_exists
     validates :email, presence: true
     validates :destination, presence: true
+    validates :email, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i , message: "email must be valid"}
+    validates :destination, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i , message: "destination must be valid"}
+    validates :destination, uniqueness: {scope: :email, message: "a redirection pair must be unique"}
 
     def domain_name_exists
         if email.present?