What is the "Return-Path" email header?
The "Return-Path" is also known as the bounce address. It's listed in an email header (therefore not directly visible to the recipient) and tells the destination mail server where to send a message if the email bounces.
Why is this important?
If the "Return-Path" header is missing, and your email bounces, some mail servers will be confused and won't know where to send the bounce notification. This means you won't be notified of the bounce, won't be able to remove that address from your list, and will continue sending to it, which can negatively impact your Sender Score (deliverability rating).
Also, we've seen cases where emails without this header will automatically end up in Spam folders, as some email clients and ISPs have very strict rules about this header.
In any case, it's best to always use it in your emails.
How do I set it up?
In whichever system or software you use to send messages to your subscribers, you need to edit its email header area and include a new field: