On 1/30/2011 6:17 PM, Daniel Bromberg wrote:
Conceivably, someone could hack a non-standard e-mail client to use the SASL name in the MAIL FROM, but tweak the 'From: ' line to anything they like (although the MAIL FROM would appear in the Return-Path / Sender fields), and this is harder to stop, correct? But we are in rare corner cases now, not ordinary users I would think.
I think alternate From: is a fairly standard feature, no hacking required. Even easier for them to use Reply-To:, which is supported by pretty much every mail client and aided by the fact that when reading mail, some popular mail clients don't show the address of the sender, only the name.
As mouss already pointed out, you can use a header_checks rule on submission/smtps that rejects mail that doesn't have 'From: .*@example.com', but it's not iron-clad protection. Also note that defining a separate header_checks for submission/smtps requires defining an alternate cleanup_service, or a separate postfix instance. Examples can be found in the archives.
-- Noel Jones
