email return path spam - What is the behavior difference between return-path, reply-to and from?

2 Answers

Another way to think about Return-Path vs Reply-To is to compare it to snail mail.

When you send an envelope in the mail, you specify a return address. If the recipient does not exist or refuses your mail, the postmaster returns the envelope back to the return address. For email, the return address is the Return-Path.

Inside of the envelope might be a letter and inside of the letter it may direct the recipient to "Send correspondence to example address". For email, the example address is the Reply-To.

In essence, a Postage Return Address is comparable to SMTP's Return-Path header and SMTP's Reply-To header is similar to the replying instructions contained in a letter.


return-path email header outlook

On our mailing application we are sending emails with the following header:


The problem that we are facing is that some email servers will bounce back a message immediately and use the from or reverse path ( instead to our bounce mgmt server. We want to know if we modify in the header the reply-to to be the same as the return-path if we will be able to catch all bounces.

Any other ideas are welcome?

We are using the following documents as references: VERP RFC Bounce Messages

SMTP Log Parsing to get Bounces

EDIT 1: A few more bits of information to see if we can get this resolve.

We want to know at what point the email server relaying the message will choose to use the reply-to versus the return-path. We have notice that when the first smtp server relaying the message gets rejected it sends it to the reply-to, but when it happens after one hop it sends it to the return-path.

I had to add a Return-Path header in emails send by a Redmine instance. I agree with greatwolf only the sender can determine a correct (non default) Return-Path. The case is the following : E-mails are send with the default email address : But we want that the real user initiating the action receives the bounce emails, because he will be the one knowing how to fix wrong recipients emails (and not the application adminstrators that have other cats to whip :-) ). We use this and it works perfectly well with exim on the application server and zimbra as the final company mail server.