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:<ubuntu@localhost>
250 2.1.0 Ok
rcpt to:<root@localhost>
250 2.1.5 Ok
rcpt to:<xxxxxx@xxxxxx.xxx>
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
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: <ubuntu@localhost>
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