Ensure every email we log is to either a User or a non-user address

application/common/models/EmailLog.php

@@ -122,6 +122,11 @@ public function rules()
                 'non_user_address',
                 'emptyIfUserIsSet',
             ],
+            [
+                'non_user_address',
+                'requiredIfUserIsEmpty',
+                'skipOnEmpty' => false,
+            ],
         ], parent::rules());
     }
 
@@ -137,4 +142,17 @@ public function emptyIfUserIsSet($attribute)
             );
         }
     }
+
+    public function requiredIfUserIsEmpty($attribute)
+    {
+        if (empty($this->user_id) && empty($this[$attribute])) {
+            $this->addError(
+                $attribute,
+                sprintf(
+                    'Either a user_id or a %s must be set',
+                    $attribute
+                )
+            );
+        }
+    }
 }

application/features/bootstrap/EmailContext.php

@@ -1356,4 +1356,15 @@ public function anEmailLogValidationErrorShouldHaveOccurred()
             'No EmailLog validation errors were found'
         );
     }
+
+    /**
+     * @When I try to log an email as sent to neither a User nor a non-user address
+     */
+    public function iTryToLogAnEmailAsSentToNeitherAUserNorANonUserAddress()
+    {
+        $this->tempEmailLog = new EmailLog([
+            'message_type' => EmailLog::MESSAGE_TYPE_ABANDONED_USERS,
+        ]);
+        $this->tempEmailLog->save();
+    }
 }

application/features/email.feature

@@ -442,3 +442,7 @@ Feature: Email
     Given a user already exists
     When I try to log an email as sent to that User and to a non-user address
     Then an email log validation error should have occurred
+
+  Scenario: Ensure each EmailLog is to either a User or a non-user address
+    When I try to log an email as sent to neither a User nor a non-user address
+    Then an email log validation error should have occurred