diff --git a/application/Espo/Core/Job/QueueName.php b/application/Espo/Core/Job/QueueName.php
new file mode 100644
index 0000000000..01e99ca4fb
--- /dev/null
+++ b/application/Espo/Core/Job/QueueName.php
@@ -0,0 +1,48 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2021 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Job;
+
+class QueueName
+{
+    /**
+     * Executes as soon as possible.
+     */
+    public const Q0 = 'q0';
+
+    /**
+     * Executes every minute.
+     */
+    public const Q1 = 'q1';
+
+    /**
+     * Executes as soon as possible. For email processing.
+     */
+    public const E0 = 'e0';
+}
diff --git a/application/Espo/Core/Mail/Importer.php b/application/Espo/Core/Mail/Importer.php
index 48d967bed8..99a3ed6433 100644
--- a/application/Espo/Core/Mail/Importer.php
+++ b/application/Espo/Core/Mail/Importer.php
@@ -40,6 +40,7 @@ use Espo\Core\{
     Notification\NotificatorParams,
     FieldProcessing\Relation\LinkMultipleSaver,
     FieldProcessing\SaverParams,
+    Job\QueueName,
 };
 
 use DateTime;
@@ -657,7 +658,7 @@ class Importer
                     'targetId' => $duplicate->id
                 ],
                 'executeAt' => $executeAt,
-                'queue' => 'q1',
+                'queue' => QueueName::Q1,
             ]);
 
             $this->entityManager->saveEntity($job);
diff --git a/application/Espo/Core/Password/Recovery.php b/application/Espo/Core/Password/Recovery.php
index 6464acd040..6b7dc9930a 100644
--- a/application/Espo/Core/Password/Recovery.php
+++ b/application/Espo/Core/Password/Recovery.php
@@ -44,6 +44,7 @@ use Espo\Core\{
     Htmlizer\Factory as HtmlizerFactory,
     Utils\TemplateFileManager,
     Utils\Log,
+    Job\QueueName,
 };
 
 use DateTime;
@@ -239,7 +240,7 @@ class Recovery
             'methodName' => 'removeChangePasswordRequestJob',
             'data' => ['id' => $passwordChangeRequest->id],
             'executeTime' => $dt->format('Y-m-d H:i:s'),
-            'queue' => 'q1',
+            'queue' => QueueName::Q1,
         ]);
 
         $timeDiff = $this->getDelay() - floor((microtime(true) - $microtime) / 1000);
diff --git a/application/Espo/Hooks/Common/AssignmentEmailNotification.php b/application/Espo/Hooks/Common/AssignmentEmailNotification.php
index 95688e6931..d82631616b 100644
--- a/application/Espo/Hooks/Common/AssignmentEmailNotification.php
+++ b/application/Espo/Hooks/Common/AssignmentEmailNotification.php
@@ -35,6 +35,7 @@ use Espo\Core\{
     Utils\Config,
     ORM\EntityManager,
     ApplicationState,
+    Job\QueueName,
 };
 
 class AssignmentEmailNotification
@@ -129,7 +130,7 @@ class AssignmentEmailNotification
                 'entityType' => $entity->getEntityType(),
             ],
             'executeTime' => date('Y-m-d H:i:s'),
-            'queue' => 'e0',
+            'queue' => QueueName::E0,
         ]);
 
         $this->entityManager->saveEntity($job);
diff --git a/application/Espo/Hooks/Common/Stream.php b/application/Espo/Hooks/Common/Stream.php
index a261914a1c..551c1ab562 100644
--- a/application/Espo/Hooks/Common/Stream.php
+++ b/application/Espo/Hooks/Common/Stream.php
@@ -35,6 +35,7 @@ use Espo\Core\{
     Utils\Metadata,
     ORM\EntityManager,
     ServiceFactory,
+    Job\QueueName,
 };
 
 use Espo\Entities\User;
@@ -321,7 +322,7 @@ class Stream
                             'entityType' => $entity->getEntityType(),
                             'entityId' => $entity->id
                         ],
-                        'queue' => 'q1'
+                        'queue' => QueueName::Q1,
                     ]);
 
                     $this->entityManager->saveEntity($job);
@@ -408,7 +409,7 @@ class Stream
                             'entityType' => $entity->getEntityType(),
                             'entityId' => $entity->id
                         ],
-                        'queue' => 'q1'
+                        'queue' => QueueName::Q1,
                     ]);
 
                     $this->entityManager->saveEntity($job);
diff --git a/application/Espo/Jobs/ProcessJobQueueE0.php b/application/Espo/Jobs/ProcessJobQueueE0.php
index 0fee47ac0c..82a185d1c5 100644
--- a/application/Espo/Jobs/ProcessJobQueueE0.php
+++ b/application/Espo/Jobs/ProcessJobQueueE0.php
@@ -33,6 +33,7 @@ use Espo\Core\{
     Job\JobManager,
     Utils\Config,
     Job\Job,
+    Job\QueueName,
 };
 
 class ProcessJobQueueE0 implements Job
@@ -51,6 +52,6 @@ class ProcessJobQueueE0 implements Job
     {
         $limit = $this->config->get('jobE0MaxPortion', 100);
 
-        $this->jobManager->processQueue('e0', $limit);
+        $this->jobManager->processQueue(QueueName::E0, $limit);
     }
 }
diff --git a/application/Espo/Jobs/ProcessJobQueueQ0.php b/application/Espo/Jobs/ProcessJobQueueQ0.php
index c369ab4a13..3eb18da4bc 100644
--- a/application/Espo/Jobs/ProcessJobQueueQ0.php
+++ b/application/Espo/Jobs/ProcessJobQueueQ0.php
@@ -33,6 +33,7 @@ use Espo\Core\{
     Job\JobManager,
     Utils\Config,
     Job\Job,
+    Job\QueueName,
 };
 
 class ProcessJobQueueQ0 implements Job
@@ -51,6 +52,6 @@ class ProcessJobQueueQ0 implements Job
     {
         $limit = $this->config->get('jobQ0MaxPortion', 200);
 
-        $this->jobManager->processQueue('q0', $limit);
+        $this->jobManager->processQueue(QueueName::Q0, $limit);
     }
 }
diff --git a/application/Espo/Jobs/ProcessJobQueueQ1.php b/application/Espo/Jobs/ProcessJobQueueQ1.php
index 5414910e24..678df8f338 100644
--- a/application/Espo/Jobs/ProcessJobQueueQ1.php
+++ b/application/Espo/Jobs/ProcessJobQueueQ1.php
@@ -33,6 +33,7 @@ use Espo\Core\{
     Job\JobManager,
     Utils\Config,
     Job\Job,
+    Job\QueueName,
 };
 
 class ProcessJobQueueQ1 implements Job
@@ -51,6 +52,6 @@ class ProcessJobQueueQ1 implements Job
     {
         $limit = $this->config->get('jobQ1MaxPortion', 500);
 
-        $this->jobManager->processQueue('q1', $limit);
+        $this->jobManager->processQueue(QueueName::Q1, $limit);
     }
 }
diff --git a/application/Espo/Services/Pdf.php b/application/Espo/Services/Pdf.php
index 24845cc9c7..dfaa9656ed 100644
--- a/application/Espo/Services/Pdf.php
+++ b/application/Espo/Services/Pdf.php
@@ -46,6 +46,7 @@ use Espo\Core\{
     ORM\Entity,
     Select\SelectBuilderFactory,
     Record\ServiceContainer,
+    Job\QueueName,
 };
 
 use Espo\{
@@ -243,7 +244,7 @@ class Pdf
                 'id' => $attachment->id
             ],
             'executeTime' => (new DateTime())->modify('+' . $this->removeMassFilePeriod)->format('Y-m-d H:i:s'),
-            'queue' => 'q1',
+            'queue' => QueueName::Q1,
         ]);
 
         $this->entityManager->saveEntity($job);
diff --git a/application/Espo/Tools/LeadCapture/LeadCapture.php b/application/Espo/Tools/LeadCapture/LeadCapture.php
index daaa6fa49a..419bf2cda1 100644
--- a/application/Espo/Tools/LeadCapture/LeadCapture.php
+++ b/application/Espo/Tools/LeadCapture/LeadCapture.php
@@ -42,6 +42,7 @@ use Espo\Core\{
     Utils\DateTime as DateTimeUtil,
     ServiceFactory,
     Utils\Log,
+    Job\QueueName,
 };
 
 use Espo\{
@@ -199,7 +200,7 @@ class LeadCapture
             'data' => (object) [
                 'id' => $uniqueId->get('name'),
             ],
-            'queue' => 'e0',
+            'queue' => QueueName::E0,
         ]);
 
         $this->entityManager->saveEntity($job);