diff --git a/src/Form/CategoryForm.php b/src/Form/CategoryForm.php
index d9effdc..78d6ffc 100644
--- a/src/Form/CategoryForm.php
+++ b/src/Form/CategoryForm.php
@@ -106,7 +106,7 @@ class CategoryForm extends EntityForm {
       }
     }
     if (!($recipients_chosen)) {
-      $form_state->setErrorByName('', $this->t('Atleast one recipient is required.'), 'error');
+      $form_state->setErrorByName('', $this->t('At least one recipient is required.'), 'error');
     }
   }
 
diff --git a/src/MassContact.php b/src/MassContact.php
index 86dfe9f..641dcd8 100644
--- a/src/MassContact.php
+++ b/src/MassContact.php
@@ -234,15 +234,9 @@ class MassContact implements MassContactInterface {
         $category_recipients = [];
         foreach ($category->getRecipients() as $plugin_id => $config) {
           $grouping = $category->getGroupingCategories($plugin_id);
-          if (empty($config['categories'])) {
-            // If no values were chosen for this grouping in this category,
-            // some other grouping should have been chosen to determine
-            // recipients. We choose users that satisfy requirements across
-            // groupings for a category, so return all the users so that the
-            // other grouping method(s) chosen will determine the recipients.
-            $category_recipients[$plugin_id] = $this->getAllActiveUsers();
-          }
-          else {
+          if (!empty($config['categories'])) {
+            // Only If values were chosen for this grouping in this category,
+            // we gather recipients.
             $category_recipients[$plugin_id] = $grouping->getRecipients($config['categories']);
           }
         }
@@ -291,13 +285,4 @@ class MassContact implements MassContactInterface {
     }
   }
 
-  /**
-   * Gets all active users on the site.
-   */
-  public function getAllActiveUsers() {
-    $query = $this->entityTypeManager->getStorage('user')->getQuery();
-    $query->condition('status', 1);
-    return $query->execute();
-  }
-
 }
diff --git a/tests/src/Functional/Form/CategoryFormTest.php b/tests/src/Functional/Form/CategoryFormTest.php
index ff61732..3535188 100644
--- a/tests/src/Functional/Form/CategoryFormTest.php
+++ b/tests/src/Functional/Form/CategoryFormTest.php
@@ -28,12 +28,15 @@ class CategoryFormTest extends MassContactTestBase {
     $this->assertSession()->addressEquals('/admin/config/mass-contact');
 
     $this->assertSession()->linkExists(t('Categories'));
-    $this->assertSession()->linkByHrefExists('/admin/config/mass-contact/settings');
+    $this->assertSession()
+      ->linkByHrefExists('/admin/config/mass-contact/settings');
     $this->clickLink(t('Categories'));
-    $this->assertSession()->addressEquals('/admin/config/mass-contact/category');
+    $this->assertSession()
+      ->addressEquals('/admin/config/mass-contact/category');
     $this->assertSession()->linkExists(t('Add category'));
     $this->clickLink(t('Add category'));
-    $this->assertSession()->addressEquals('/admin/config/mass-contact/category/add');
+    $this->assertSession()
+      ->addressEquals('/admin/config/mass-contact/category/add');
 
     // Create a category via the UI.
     $edit = [
@@ -67,7 +70,9 @@ class CategoryFormTest extends MassContactTestBase {
     $edit['recipients[role][conjunction]'] = 'OR';
     $this->drupalPostForm(NULL, $edit, t('Save'));
 
-    \Drupal::entityTypeManager()->getStorage('mass_contact_category')->resetCache();
+    \Drupal::entityTypeManager()
+      ->getStorage('mass_contact_category')
+      ->resetCache();
     /** @var \Drupal\mass_contact\Entity\MassContactCategoryInterface $category */
     $category = MassContactCategory::load($edit['id']);
     $this->assertEquals($edit['label'], $category->label());
@@ -81,6 +86,17 @@ class CategoryFormTest extends MassContactTestBase {
       'conjunction' => 'OR',
     ];
     $this->assertEquals($expected, $category->getRecipients()['role']);
+
+    // Test that when no recipients are selected, a validation error is thrown.
+    $this->drupalGet('/admin/config/mass-contact/category/add');
+    // Create a category via the UI.
+    $edit = [
+      'id' => Unicode::strtolower($this->randomMachineName()),
+      'label' => $this->randomString(),
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertSession()
+      ->pageTextContains('At least one recipient is required.');
   }
 
-}
+}
\ No newline at end of file