How to Set the Return-Path For a Magento 1 Shop
When you send emails from your Magento shop with no return-path set, the return-path will default to email@example.com. This email address may be recognised as a spam address by spam filters, as it is a very generic email used on all Hypernodes with the same email configuration.
To avoid outgoing email being detected as spam, you should change the email return-path for your outgoing email to a valid email address (e.g. firstname.lastname@example.org) which can be managed with your own SPF settings.
If the recipient is using SAV (Sender Address Verification), and the e-mail address is not reachable, or the SPF record does not match the email source, a spamfilter could see this as a spam message.
Change Your Return-Path
Every email has two senders. The first sender is the From line that is seen in the mailclient as the recipient. The other is the Return-Path. The latter address is used for errors (bounces) to control the delivery of the mail to the sender.
Set the Return-Path For a Magento 1 Shop
To set the return-path for your Magento 1 shop, log in on the admin panel and follow the instructions:
Login to your Magento admin panel.
Navigate to System > Configuration in the top navigation panel.
In the left navigation panel, select System, and select Mail Sending Settings in the dropdown:
Change Set Return-Path to “specified”.
In the Return-Path Email field, set a valid email address.
Click Save Config to save the changes.