diff --git a/admin-dev/ajax.php b/admin-dev/ajax.php
index b2ac42f51..ee25cf7b3 100644
--- a/admin-dev/ajax.php
+++ b/admin-dev/ajax.php
@@ -729,23 +729,34 @@ if (Tools::isSubmit('syncImapMail'))
 	OR !$port = Configuration::get('PS_SAV_IMAP_PORT')
 	OR !$user = Configuration::get('PS_SAV_IMAP_USER')
 	OR !$password = Configuration::get('PS_SAV_IMAP_PWD'))
-	die('{"hasError" : true, "errors" : "Configuration is not correct"}');
-
+	die('{"hasError" : true, "errors" : ["Configuration is not correct"]}');
+	
+	if (!function_exists('imap_open'))
+		die('{"hasError" : true, "errors" : ["imap is not installed on this server"]}');
+	
 	$mbox = @imap_open('{'.$url.':'.$port.'}', $user, $password);
-
+	
+	//checks if there is no error when connecting imap server
 	$errors = imap_errors();
+	$str_errors = '';
+	$str_error_delete = '';
 	if (sizeof($errors))
 	{
 		$str_errors = '["';
 		foreach($errors as $error)
-			$str_errors .= $error.',';
-		$str_errors = rtrim($str_errors, ',').'"]';
+			$str_errors .= '"'.$error.'",';
+		$str_errors = rtrim($str_errors, ',').'';
 	}
+	
+	//checks if imap connexion is active
 	if (!$mbox)
-		die('{"hasError" : true, "errors" : ["Can not connect to the mailbox"]}');
-
+		die('{"hasError" : true, "errors" : ["Cannot connect to the mailbox"]}');
+	
+	//Returns information about the current mailbox. Returns FALSE on failure.
 	$check = imap_check($mbox);
-
+	if ($check)
+		die('{"hasError" : true, "errors" : ["Fail to get information about the current mailbox"]}');
+	
 	if ($check->Nmsgs == 0)
 		die('{"hasError" : true, "errors" : ["NO message to sync"]}');
 
@@ -757,16 +768,18 @@ if (Tools::isSubmit('syncImapMail'))
 	   		$subject = $overview->subject;
 	   	else
 	   		$subject = '';
-
-	    $md5 = md5($overview->date.$overview->from.$subject);
+	   	
+		//Creating an md5 to check if message has been allready processed
+	    $md5 = md5($overview->date.$overview->from.$subject.$overview->msgno);
 	    $exist = Db::getInstance()->getValue(
-			    'SELECT md5_header
+			    'SELECT `md5_header`
 			    FROM `'._DB_PREFIX_.'customer_message_sync_imap`
-			    WHERE md5_header = \''.pSQL($md5).'\'');
+			    WHERE `md5_header` = \''.pSQL($md5).'\'');
 	    if ($exist)
 	    {
 			if (Configuration::get('PS_SAV_IMAP_DELETE_MSG'))
-				imap_delete($mbox, $overview->msgno);
+				if (!imap_delete($mbox, $overview->msgno))
+					$str_error_delete = ', "Fail to delete message"';
 	    }
 	    else
 	    {
@@ -787,12 +800,12 @@ if (Tools::isSubmit('syncImapMail'))
 					$cm->add();
 				}
 			}
-			Db::getInstance()->execute('INSERT INTO `'._DB_PREFIX_.'customer_message_sync_imap` VALUES (\''.pSQL($md5).'\')');
+			Db::getInstance()->execute('INSERT INTO `'._DB_PREFIX_.'customer_message_sync_imap` (`md5_header`) VALUES (\''.pSQL($md5).'\')');
 	    }
 	}
 	imap_expunge($mbox);
 	imap_close($mbox);
-	die('{"hasError" : false, "errors" : '.$str_errors.'}');
+	die('{"hasError" : false, "errors" : '.$str_errors.$str_errors_delete.'"]}');
 }
 
 /* Modify attribute position */
diff --git a/admin-dev/tabs/AdminCustomerThreads.php b/admin-dev/tabs/AdminCustomerThreads.php
index 8ef4282d1..7b2646206 100644
--- a/admin-dev/tabs/AdminCustomerThreads.php
+++ b/admin-dev/tabs/AdminCustomerThreads.php
@@ -94,7 +94,7 @@ class AdminCustomerThreads extends AdminTab
 					'PS_SAV_IMAP_PORT' => array('title' => $this->l('Imap port'), 'desc' => $this->l('Port to use to connect imap server'), 'type' => 'text', 'defaultValue' => 143, 'visibility' => Shop::CONTEXT_ALL),
 					'PS_SAV_IMAP_USER' => array('title' => $this->l('Imap user'), 'desc' => $this->l('User to use to connect imap server'), 'type' => 'text', 'size' => 40, 'visibility' => Shop::CONTEXT_ALL),
 					'PS_SAV_IMAP_PWD' => array('title' => $this->l('Imap password'), 'desc' => $this->l('Password to use to connect imap server'), 'type' => 'text', 'size' => 40, 'visibility' => Shop::CONTEXT_ALL),
-					'PS_SAV_IMAP_DELETE_MSG' => array('title' => $this->l('Delete messages'), 'desc' => $this->l('Deletes message after sync. If you do not active this option, the sync will be longer'), 'cast' => 'intval', 'type' => 'select', 'identifier' => 'value', 'list' => array(
+					'PS_SAV_IMAP_DELETE_MSG' => array('title' => $this->l('Deletes messages'), 'desc' => $this->l('Deletes message after sync. If you do not active this option, the sync will be longer'), 'cast' => 'intval', 'type' => 'select', 'identifier' => 'value', 'list' => array(
 						'0' => array('value' => 0, 'name' => $this->l('No')), 
 						'1' => array('value' => 1, 'name' => $this->l('Yes')) 
 					), 'visibility' => Shop::CONTEXT_ALL)
@@ -196,6 +196,7 @@ class AdminCustomerThreads extends AdminTab
 						'{reply}' => Tools::nl2br(Tools::getValue('reply_message')),
 						'{link}' => Tools::url($this->context->link->getPageLink('contact', true), 'id_customer_thread='.(int)($ct->id).'&token='.$ct->token),
 					);
+					//#ct == id_customer_thread    #tc == token of thread   <== used in the synchronization imap
 					if (Mail::Send($ct->id_lang, 'reply_msg', Mail::l('An answer to your message is available').' #ct'.$ct->id.'#tc'.$ct->token, 
 						$params, Tools::getValue('msg_email'), NULL, NULL, NULL, $fileAttachment, NULL, 
 						_PS_MAIL_DIR_, true))
@@ -644,14 +645,17 @@ class AdminCustomerThreads extends AdminTab
 			</div>
 		</fieldset><br/>
 		<script type="text/javascript"> 
+			var ajaxQueries = new Array();
 			function run_sync () {
 				$(\'#ajax_error\').html(\'\');
 				$(\'#ajax_error\').hide();
 				$(\'#ajax_conf\').html(\'\');
 				$(\'#ajax_conf\').hide();
-
+				for(i = 0; i < ajaxQueries.length; i++)
+					ajaxQueries[i].abort();
+				ajaxQueries = new Array();
 				$(\'#ajax_loader\').html(\'<img src="'._PS_ADMIN_IMG_.'ajax-loader.gif">\');
-				$.ajax({
+				ajaxQuery = $.ajax({
 					type: "POST",
 					url: "ajax.php",
 					data: "syncImapMail=1",
@@ -660,7 +664,7 @@ class AdminCustomerThreads extends AdminTab
 						jsonError = \'\';
 						if (jsonData.hasError)
 						{
-							for (i=0;i<jsonData.errors.length;i++)
+							for (i=0;i < jsonData.errors.length;i++)
 								jsonError = jsonError+\'<li>\'+jsonData.errors[i]+\'</li>\';
 							$(\'#ajax_error\').html(\'<ul>\'+jsonError+\'</ul>\');
 							$(\'#ajax_error\').fadeIn();
@@ -668,7 +672,7 @@ class AdminCustomerThreads extends AdminTab
 						else
 						{
 							jsonError = \'<li>'.$this->l('Sync success').'</li>\';
-							for (i=0;i<jsonData.errors.length;i++)
+							for (i=0;i < jsonData.errors.length;i++)
 								jsonError = jsonError+\'<li>\'+jsonData.errors[i]+\'</li>\';
 							$(\'#ajax_conf\').html(\'<ul>\'+jsonError+\'</ul>\');
 							$(\'#ajax_conf\').fadeIn();
@@ -677,9 +681,10 @@ class AdminCustomerThreads extends AdminTab
 						$(\'#ajax_loader\').html(\'\');
 					},
 					error: function(XMLHttpRequest, textStatus, errorThrown) {
-						alert("TECHNICAL ERROR: unable to refresh the cart.\n\nDetails:\nError thrown: " + XMLHttpRequest + "\n" + \'Text status: \' + textStatus);
+						alert("TECHNICAL ERROR: unable to sync.\n\nDetails:\nError thrown: " + XMLHttpRequest + "\n" + \'Text status: \' + textStatus);
 					}
 				});
+				ajaxQueries.push(ajaxQuery);
 				
 			};
 		</script>';
diff --git a/translations/fr/admin.php b/translations/fr/admin.php
index 823f49b03..bc0e50159 100644
--- a/translations/fr/admin.php
+++ b/translations/fr/admin.php
@@ -560,11 +560,11 @@ $_LANGADM['AdminCustomerThreadsa81b40d671a82de3bc3550b878234dd6'] = 'Url pour le
 $_LANGADM['AdminCustomerThreadscd16a15c486d2e183732556f779968c9'] = 'Port IMAP';
 $_LANGADM['AdminCustomerThreads8a29ff48f49ffe61e4e886a04cff2eb6'] = 'Port à utiliser pour se connecter le serveur imap';
 $_LANGADM['AdminCustomerThreads678b57a794c6976ac961df8a32394def'] = 'Utilisateur IMAP';
-$_LANGADM['AdminCustomerThreads0882db19e4fce8cbaff75c9dc2fb1166'] = 'L\'utilisateur à utiliser pour se connecter le serveur IMAP';
+$_LANGADM['AdminCustomerThreads0882db19e4fce8cbaff75c9dc2fb1166'] = 'Utilisateur pour se connecter le serveur IMAP';
 $_LANGADM['AdminCustomerThreads22e38bd8ea7e850765045720e0b9cf5d'] = 'Mot de passe IMAP';
 $_LANGADM['AdminCustomerThreadsa5bf021c18a4c0891b491c07d3555b86'] = 'Mot de passe à utiliser pour se connecter le serveur IMAP';
-$_LANGADM['AdminCustomerThreadsca7e64e3f55ef8e0f50818d8117d26cc'] = 'Supprimer des messages';
-$_LANGADM['AdminCustomerThreadsbbd8156a324aee57b7186991acf82d0d'] = 'Supprime le message après la synchronisation. Si vous n\'avez pas active cette option, la synchronisation sera plus long';
+$_LANGADM['AdminCustomerThreadsfaa07c5eadea7dd34bfc379d7bfd7c67'] = 'Supprime les messages';
+$_LANGADM['AdminCustomerThreadsbbd8156a324aee57b7186991acf82d0d'] = 'Supprime le message après la synchronisation. Si vous n\'avez pas activée cette option, la synchronisation sera plus longue';
 $_LANGADM['AdminCustomerThreadsbafd7322c6e97d25b6299b5d6fe8920b'] = 'Non';
 $_LANGADM['AdminCustomerThreads93cba07454f06a4a960172bbd6e2a435'] = 'Oui';
 $_LANGADM['AdminCustomerThreadsd21b5a78517318e6d35414d4217950ce'] = 'Message transmis à';
@@ -628,7 +628,7 @@ $_LANGADM['AdminCustomerThreads694e8d1f2ee056f98ee488bdc4982d73'] = 'Quantité';
 $_LANGADM['AdminCustomerThreadsd8e87c0927539672f54462c837be0b7f'] = 'Synchroniser';
 $_LANGADM['AdminCustomerThreadsa19330a6fc36ebae6683cc023e295687'] = 'Exécutez la synchronisation';
 $_LANGADM['AdminCustomerThreads22009610f18142abea939bc2f1836a81'] = 'Cliquez pour synchroniser les mails automatiquement';
-$_LANGADM['AdminCustomerThreads1e65b02f3464a517e0946a46d496327c'] = 'Synchronisation avec succès';
+$_LANGADM['AdminCustomerThreads1e65b02f3464a517e0946a46d496327c'] = 'Synchronisation effectué avec succès';
 $_LANGADM['AdminCustomersd1457b72c3fb323a2671125aef3eab5d'] = '?';
 $_LANGADM['AdminCustomersb718adec73e04ce3ec720dd11a06a308'] = 'ID';
 $_LANGADM['AdminCustomers019ec3132cdf8ee0f2e2a75cf5d3e459'] = 'Sexe';