Email Auto-Replies not going to Reply-To Address

Question

I have a web app that sends emails via smtp on behalf of the user to their customers. I am able to put the user's email in the reply-to of the email and this works for normal email use for the users. In the case the recipient has an auto-responder or the email entered was incorrect email, the auto replies go to the sender not the reply-to. The sender inbox is unmonitored.

The sender email service is using and Office365 account.

What are my options to get the auto replies and returned emails to the reply-to email?

Answer 1

This may be because the autoresponders don't regard their messages as replies, but rather as messages from the email system itself.

Your mail has three or four addresses related to the sender, which generally show up at the recipient as Return-Path, Sender, From and Reply-To. Return-Path is who should get error messages and other messages from the email system itself, Sender and From are the address that should be displayed as having sent the mail and Reply-To is the address to which the addressee's replies should be directed. (Sender and From are only very rarely different these days, but historically Sender might be e.g. a particular member of a team while From is the team's shared address.)

Many autoresponders respond to the address that shows up as Return-Path in the final message (it's also called the envelope from address), so your options are:

• use the user's address as envelope from
• set up a forwarding scheme so that autoresponses are suitably forwarded

The first is very tricky wrt. DKIM, DMARC etc, so you'll probably find the second one simpler, even though it requires you to filter spam and perhaps more.