Explaining VERP

Question

I am in the middle of making a bounce detection program, that reads bounce mails. Our setup is that we are sending out emails, adding a [email protected] to the sent mails. Some of the recipients does not exist anymore and therefor we want to read the bounce, and detect whom it was sent to. I have crumbled over this for a day or two now doing my googling and so. Now I have stumbled over something named VERP, Variable envelope return path. But is there someone here who can explain the technic to me in "human" terms?

I understand it in this way: send a mail to a recipient with a "FROM:" header set to [email protected].

But how do the recipient mail server deduct the return address in the FROM header if the recipient does not exists? Does it deduct it from the Return-Path instead set in the sent mail?

Hope someone understands my question, and can explain me how it works, or maybe tell me an alternat way of doing it.

Chukker

no, not the From: header SMTP MAIL FROM: AKA "Return-Path" – William

Answer 1

Imagine this:

You send a newsletter to :

• [email protected]
• [email protected]
• [email protected]

Bob and Jane addresses are no longer existent.

Therefore for each mail address that you target you generate a unique Return-Path: address like so :

• For Bob : [email protected]
• For Jane : [email protected]
• For Steve : [email protected]

Then checking your catch-all account on bounce.yourdomain.com (programatically) you find two emails :

One for [email protected] and one for [email protected].

You previously stored somewhere that 1 belongs to bob and 2 to Jane so you remove them from the newsletter list.

Underpants

Hi Andrei, how do you check your catch-all account? Thanks, I mean how do you even set a catch all account? Thanks... – Gracious