One additional test was performed to properly verify Postfix's installation. * When installing, I chose 'Internet site'. Following this rationale, messages should be sendable to the outside world, barring possible spam-filtering-related issues. Test was run manually, by speaking SMTP to Postfix: {{{ ubuntu@domU-12-31-39-00-49-E5:~$ telnet 127.0.0.1 25 Trying 127.0.0.1... Connected to 127.0.0.1. Escape character is '^]'. 220 domU-12-31-39-00-49-E5.compute-1.internal ESMTP Postfix (Ubuntu) ehlo localhost 250-domU-12-31-39-00-49-E5.compute-1.internal 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN mail from: 250 2.1.0 Ok rcpt to: 250 2.1.5 Ok rcpt to: 250 2.1.5 Ok data 354 End data with . Subject: Test message, testing ec2 instance i-cea11da6 To: xxxx xxxxxx, root This is a test message, please disregard. / Matt . 250 2.0.0 Ok: queued as 2CABC406E7 quit 221 2.0.0 Bye Connection closed by foreign host. }}} The message was successfully received (although treated as spam, as expected): {{{ Delivered-To: xxxxxx@xxxxxx.xxx Received: by 10.210.90.20 with SMTP id n20cs153202ebb; Mon, 19 Oct 2009 18:58:02 -0700 (PDT) Received: by 10.220.69.90 with SMTP id y26mr9811387vci.51.1256003881410; Mon, 19 Oct 2009 18:58:01 -0700 (PDT) Return-Path: Received: from domU-12-31-39-00-49-E5.compute-1.internal (ec2-174-129-35-78.compute-1.amazonaws.com [174.129.35.78]) by mx.google.com with ESMTP id 26si6408327vws.66.2009.10.19.18.58.00; Mon, 19 Oct 2009 18:58:01 -0700 (PDT) Received-SPF: neutral (google.com: 174.129.35.78 is neither permitted nor denied by domain of ubuntu@localhost) client-ip=174.129.35.78; Authentication-Results: mx.google.com; spf=neutral (google.com: 174.129.35.78 is neither permitted nor denied by domain of ubuntu@localhost) smtp.mail=ubuntu@localhost Received: from localhost (localhost [127.0.0.1]) by domU-12-31-39-00-49-E5.compute-1.internal (Postfix) with ESMTP id 2CABC406E7; Tue, 20 Oct 2009 01:56:56 +0000 (UTC) Subject: Test message, testing ec2 instance i-cea11da6 To: xxxx@domU-12-31-39-00-49-E5.compute-1.internal, xxxxxx@domU-12-31-39-00-49-E5.compute-1.internal, root@domU-12-31-39-00-49-E5.compute-1.internal Message-Id: <20091020015705.2CABC406E7@domU-12-31-39-00-49-E5.compute-1.internal> Date: Tue, 20 Oct 2009 01:56:56 +0000 (UTC) From: ubuntu@localhost This is a test message, please disregard. / Matt }}}