diff --git a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
index b425719818..882d2cfe3d 100644
--- a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
+++ b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
@@ -933,9 +933,25 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
                     
                     // set subject line
                     String subject = (String)ruleAction.getParameterValue(PARAM_SUBJECT);
-                    List<Object> subjectParams = (List<Object>)ruleAction.getParameterValue(PARAM_SUBJECT_PARAMS);
-                    subjectParams = subjectParams == null ? new ArrayList<Object>() : subjectParams;
-                    String localizedSubject = getLocalizedSubject(subject, subjectParams.toArray(), locale);
+                    Object subjectParamsObject = ruleAction.getParameterValue(PARAM_SUBJECT_PARAMS);
+                    Object[] subjectParams = null;
+                    //Javasctipt pass SubjectParams as ArrayList. see MNT-12534 
+                    if (subjectParamsObject instanceof List)
+                    {
+                        subjectParams = ((List<Object>)subjectParamsObject).toArray();
+                    }
+                    else if (subjectParamsObject instanceof Object[])
+                    {
+                        subjectParams = (Object[])subjectParamsObject;
+                    }
+                    else
+                    {
+                        if (subjectParamsObject != null)
+                        {
+                            subjectParams = new Object[]{subjectParamsObject.toString()};
+                        }
+                    }
+                    String localizedSubject = getLocalizedSubject(subject, subjectParams, locale);
                     if (locale == null)
                     {
                         // process the template against the model
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 232cd4ee40..b4a2d81853 100644
--- a/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java
+++ b/source/test-java/org/alfresco/repo/action/executer/AbstractMailActionExecuterTest.java
@@ -25,6 +25,7 @@ import java.util.Arrays;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import javax.mail.Address;
@@ -54,6 +55,7 @@ import org.alfresco.service.cmr.security.PermissionService;
 import org.alfresco.service.cmr.security.PersonService;
 import org.alfresco.service.namespace.QName;
 import org.alfresco.service.transaction.TransactionService;
+import org.alfresco.util.Pair;
 import org.alfresco.util.PropertyMap;
 import org.alfresco.util.test.junitrules.AlfrescoPerson;
 import org.alfresco.util.test.junitrules.ApplicationContextInit;
@@ -384,6 +386,35 @@ public abstract class AbstractMailActionExecuterTest
     	}
     }
 
+    @Test
+    public void testPrepareEmailSubjectParams()
+    {
+        Action mailAction = ACTION_SERVICE.createAction(MailActionExecuter.NAME);
+        mailAction.setParameterValue(MailActionExecuter.PARAM_TO, "some.bodyelse@example.com");
+        mailAction.setParameterValue(MailActionExecuter.PARAM_TEMPLATE, "alfresco/templates/mail/test.txt.ftl");
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT, "Test Subject Params");
+        mailAction.setParameterValue(MailActionExecuter.PARAM_TEMPLATE_MODEL, getModel());
+        Pair<String, Locale> recipient = new Pair<String, Locale>("test", Locale.ENGLISH);
+        
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT_PARAMS, new Object[] {"Test", "Subject", "Params", "Object", "Array"});
+        Assert.assertNotNull("We should support Object[] value for PARAM_SUBJECT_PARAMS", ACTION_EXECUTER.prepareEmail(mailAction, null, recipient, null));
+        
+        ArrayList<Object> params = new ArrayList<Object>();
+        params.add("Test");
+        params.add("Subject");
+        params.add("Params");
+        params.add("ArrayList");
+        
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT_PARAMS, params);
+        Assert.assertNotNull("We should support List<Object> value for PARAM_SUBJECT_PARAMS", ACTION_EXECUTER.prepareEmail(mailAction, null, recipient, null));
+        
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT_PARAMS, "Test Subject Params Single String");
+        Assert.assertNotNull("We should support String value for PARAM_SUBJECT_PARAMS", ACTION_EXECUTER.prepareEmail(mailAction, null, recipient, null));
+        
+        mailAction.setParameterValue(MailActionExecuter.PARAM_SUBJECT_PARAMS, null);
+        Assert.assertNotNull("We should support null value for PARAM_SUBJECT_PARAMS", ACTION_EXECUTER.prepareEmail(mailAction, null, recipient, null));
+    }
+
     /**
      * Creates a test user with the specified username and optionally custom email.
      *