Best way to send email from my web app so it looks like it came from my users account

To: [email protected]
Subject: [Test Blog] =?UTF-8?B?aGVsbA==?=
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
From:=?UTF-8?B?aGVsbA==?=<[email protected]>
Message-Id: <[email protected]>
Date: Sat,  7 Feb 2009 23:47:37 +0000 (UTC)
Return-Path: [email protected]

email.from = "From Name <[email protected]>";