diff --git a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
index afdb4c092f..46ccdee71d 100644
--- a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
+++ b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2013 Alfresco Software Limited.
+ * Copyright (C) 2005-2014 Alfresco Software Limited.
  *
  * This file is part of Alfresco
  *
@@ -1336,7 +1336,13 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
             // If the domain is null, then the beahviour here varies depending on whether it's a single tenant or multi-tenant cloud.
             if (personExists(user))
             {
-                localeString = (String) preferenceService.getPreference(user, "locale");
+                localeString = AuthenticationUtil.runAsSystem(new RunAsWork<String>()
+                {
+                    public String doWork() throws Exception 
+                    {
+                        return (String) preferenceService.getPreference(user, "locale");
+                    };
+                }); 
             }
             // else leave it as null - there's no tenant, no user for that username, so we can't get a preferred locale.
         }
diff --git a/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java b/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java
index e2a4018a8b..230400f712 100644
--- a/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java
+++ b/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java
@@ -33,6 +33,7 @@ import javax.mail.internet.MimeMessage;
 import org.alfresco.model.ContentModel;
 import org.alfresco.repo.management.subsystems.ApplicationContextFactory;
 import org.alfresco.repo.security.authentication.AuthenticationUtil;
+import org.alfresco.repo.security.authentication.AuthenticationUtil.RunAsWork;
 import org.alfresco.repo.tenant.TenantService;
 import org.alfresco.repo.tenant.TenantUtil;
 import org.alfresco.repo.tenant.TenantUtil.TenantRunAsWork;
@@ -336,8 +337,8 @@ public abstract class AbstractMailActionExecuterTest
     	{
             final String USER1 = "test_user1";
             final String USER2 = "test_user2";
-            createUser(USER1);
-            NodeRef userNode = createUser(USER2);
+            createUser(USER1, null);
+            NodeRef userNode = createUser(USER2, null);
             groupName = AUTHORITY_SERVICE.createAuthority(AuthorityType.GROUP, "testgroup1");
             AUTHORITY_SERVICE.addAuthority(groupName, USER1);
             AUTHORITY_SERVICE.addAuthority(groupName, USER2);
@@ -373,15 +374,59 @@ public abstract class AbstractMailActionExecuterTest
     	}
     }
 
-    private NodeRef createUser(String userName)
+    /**
+     * Creates a test user with the specified username and optionally custom email.
+     * 
+     * @param userName
+     * @param email Optional, if not specified assigned to <code>userName + "@email.com"</code>
+     * @return
+     */
+    private NodeRef createUser(String userName, String email)
     {
         PropertyMap personProps = new PropertyMap();
         personProps.put(ContentModel.PROP_USERNAME, userName);
         personProps.put(ContentModel.PROP_FIRSTNAME, userName);
         personProps.put(ContentModel.PROP_LASTNAME, userName);
-        personProps.put(ContentModel.PROP_EMAIL, userName + "@email.com");
+        if (email != null)
+        {
+            personProps.put(ContentModel.PROP_EMAIL, email);
+        }
+        else
+        {
+            personProps.put(ContentModel.PROP_EMAIL, userName + "@email.com");
+        }
 
         return PERSON_SERVICE.createPerson(personProps);
     }
 
+    /**
+     * Test for MNT-10874
+     * @throws Exception 
+     */
+    @Test
+    public void testUserWithNonExistingTenant() throws Exception
+    {
+        final String USER_WITH_NON_EXISTING_TENANT = "test_user_non_tenant@non_existing_tenant.com";
+        
+        createUser(USER_WITH_NON_EXISTING_TENANT, USER_WITH_NON_EXISTING_TENANT);
+        
+        final Action mailAction = ACTION_SERVICE.createAction(MailActionExecuter.NAME);
+        mailAction.setParameterValue(MailActionExecuter.PARAM_TO, USER_WITH_NON_EXISTING_TENANT);
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT, "Testing");
+        mailAction.setParameterValue(MailActionExecuter.PARAM_TEXT, "This is a test message.");
+
+        // run as non admin and non system
+        AuthenticationUtil.setFullyAuthenticatedUser(BRITISH_USER.getUsername());
+        TRANSACTION_SERVICE.getRetryingTransactionHelper().doInTransaction(new RetryingTransactionCallback<Void>()
+        {
+            @Override
+            public Void execute() throws Throwable
+            {
+                ACTION_EXECUTER.executeImpl(mailAction, null);
+                return null;
+            }
+        });
+        
+        AuthenticationUtil.clearCurrentSecurityContext();
+    }
 }