Question

I’m having a problem getting emails to bounce to a specific email address, different to the From address.

A particular client requires that we send emails from a specific email address (call it [e-mail]). Our Exchange admins have created an account on the Exchange box so that we can log in and send from that address. Our Exchange server is spoofing that address / domain. This works fine.

Unfortunately the emails sent from [e-mail] are not bouncing back to us. They are presumably bouncing back to the contact account at clientcompany.com (which may or may not exist).

I’ve inserted a header Return-Path=[e-mail] with the assumption that this field determines where bouncebacks are sent. Other documents indicate that this field should never be populated by the originating SMTP system. Other websites again talk about a field called Errors-To which is apparently non-standard.

So – which field is the correct one, and what does it depend on?
Any ideas why my Return-Path is not working?

I’d really like to get Exchange to correctly bounce a message addressed to an invalid server!

update:

Continuing to dig, and my Return-Path work was only adding an extended property at the end of the header block, but Exchange appears to be still adding its own Return-Path value at the top.

Delivered-To: [e-mail] 
Received: by 1.1.1.1 with SMTP ... 
Return-Path: <[e-mail]> 
Received: from ... ... 
...
Subject: Test 
Message-ID: ... 
Return-Path: [e-mail]

According to the Microsoft.com, I cannot set the Return-Path as it is determined by the MAIL FROM – which seems consistent with what I’ve previously read. But now I’m stuck – how do I change this MAIL FROM value programmatically within Exchange 2007?

Answer 1

You might want to check if the header is correctly set. Check the headers of your email and look for:

Return-Path: [e-mail]

Return-Path is the correct field according to RFC (IIRC) but not all Mail Servers implement that correctly.