diff --git a/lib/Entities/SubscriberCustomFieldEntity.php b/lib/Entities/SubscriberCustomFieldEntity.php
index 43880baf90..ea12dec2be 100644
--- a/lib/Entities/SubscriberCustomFieldEntity.php
+++ b/lib/Entities/SubscriberCustomFieldEntity.php
@@ -6,6 +6,8 @@ use MailPoet\Doctrine\EntityTraits\AutoincrementedIdTrait;
 use MailPoet\Doctrine\EntityTraits\CreatedAtTrait;
 use MailPoet\Doctrine\EntityTraits\SafeToOneAssociationLoadTrait;
 use MailPoet\Doctrine\EntityTraits\UpdatedAtTrait;
+use MailPoet\InvalidStateException;
+use MailPoet\Util\DateConverter;
 use MailPoetVendor\Doctrine\ORM\Mapping as ORM;
 
 /**
@@ -36,14 +38,17 @@ class SubscriberCustomFieldEntity {
    */
   private $value;
 
+  /**
+   * @param string|array|null $value
+   */
   public function __construct(
     SubscriberEntity $subscriber,
     CustomFieldEntity $customField,
-    string $value
+    $value
   ) {
     $this->subscriber = $subscriber;
     $this->customField = $customField;
-    $this->value = $value;
+    $this->setValue($value);
   }
 
   /**
@@ -64,4 +69,51 @@ class SubscriberCustomFieldEntity {
   public function getCustomField() {
     return $this->customField;
   }
+
+  /**
+   * @param string|array|null $value
+   */
+  public function setValue($value): void {
+    $customField = $this->getCustomField();
+    if (!$customField instanceof CustomFieldEntity) {
+      throw new InvalidStateException('CustomField has to be set');
+    }
+
+    // format custom field data depending on type
+    if (is_array($value) && $customField->getType() === CustomFieldEntity::TYPE_DATE) {
+      $customFieldParams = $customField->getParams();
+      $dateFormat = $customFieldParams['date_format'] ?? null;
+      $dateType = isset($customFieldParams['date_type']) ? $customFieldParams['date_type'] : 'year_month_day';
+      switch ($dateType) {
+        case 'year_month_day':
+          $value = str_replace(['DD', 'MM', 'YYYY'], [$value['day'], $value['month'], $value['year']], $dateFormat);
+          break;
+
+        case 'year_month':
+          $value = str_replace(['MM', 'YYYY'], [$value['month'], $value['year']], $dateFormat);
+          break;
+
+        case 'month':
+          $value = (int)$value['month'] === 0 ? '' : sprintf('%s', $value['month']);
+          break;
+
+        case 'day':
+          $value = (int)$value['day'] === 0 ? '' : sprintf('%s', $value['day']);
+          break;
+
+        case 'year':
+          $value = (int)$value['year'] === 0 ? '' : sprintf('%04d', $value['year']);
+          break;
+      }
+
+      if (!empty($value) && is_string($value)) {
+        $value = (new DateConverter())->convertDateToDatetime($value, $dateFormat);
+      }
+    }
+
+    if (is_array($value)) {
+      throw new InvalidStateException('Final value has to be string');
+    }
+    $this->value = (string)$value;
+  }
 }