Here's the header part of the 2 mails I receive when they are duplicate. From what I can understand, it seems that there's only one connection made to Postfix, but Postfix send the mail to LMTP, but made a new copy and send it to itself, which is then sent to LMTP too.
Does it means something else? Daniel ------------------------------------------------------------------- Message #1 ------------------------------------------------------------------- Received: from localhost (homer.mydomain.com [10.0.32.13]) by mail.mydomain.com (Postfix) with ESMTP id 561804498EF for ; Sat, 21 Feb 2009 13:37:41 -0500 (EST) Received: from mail.mydomain.com ([10.0.32.13]) by localhost (homer.mydomain.com [10.0.32.13]) (amavisd-new, port 10024) with LMTP id NHSD4caH1jdE for ; Sat, 21 Feb 2009 13:37:38 -0500 (EST) Received: from [10.0.0.120] (ip-xxx.xxx.xxx.xxx.dsl-xxx.xxx [xxx.xxx.xxx.xxx]) by mail.mydomain.com (Postfix) with ESMTP id 0421137074D for ; Sat, 21 Feb 2009 13:37:37 -0500 (EST) ------------------------------------------------------------------- Message #2 ------------------------------------------------------------------- Received: from localhost (homer.mydomain.com [10.0.32.13]) by mail.mydomain.com (Postfix) with ESMTP id 79CF64498EC for ; Sat, 21 Feb 2009 13:37:41 -0500 (EST) Received: from mail.mydomain.com ([10.0.32.13]) by localhost (homer.mydomain.com [10.0.32.13]) (amavisd-new, port 10024) with LMTP id QgPsqaEw4tIc for ; Sat, 21 Feb 2009 13:37:38 -0500 (EST) by mail.mydomain.com (Postfix, from userid 207) id 314664498FC; Sat, 21 Feb 2009 13:37:38 -0500 (EST)