Index: src/main/java/org/apache/james/queue/activemq/FileSystemBlobStrategy.java
===================================================================
--- src/main/java/org/apache/james/queue/activemq/FileSystemBlobStrategy.java	(revision 1180047)
+++ src/main/java/org/apache/james/queue/activemq/FileSystemBlobStrategy.java	(revision )
@@ -144,11 +144,16 @@
         File queueF = fs.getFile(queueUrl);
 
         // check if we need to create the queue folder
-        if (queueF.exists() == false) {
+        if (!queueF.exists()) {
             if (!queueF.mkdirs()) {
+                // It could be that queueF.mkdirs() returned false because queueF has been created
+                // in the meantime (eg. by a different thread). Only throw an exception if this is
+                // not the case.
+                if (!queueF.exists()) {
-                throw new IOException("Unable to create directory " + queueF.getAbsolutePath());
-            }
-        }
+                    throw new IOException("Unable to create directory " + queueF.getAbsolutePath());
+                }
+            }
+        }
         return fs.getFile(queueUrl + "/" + filename);
 
     }