This can be done using custom envelope or return-path
How to setup custom envelope?
Step 1: Create a sub-domain
[SUB-DOMAIN] = delivery.yourdomain.com
Example: If your main domain is xyz.com, then create a sub-domain delivery.xyz.com and follow the next steps.
Step 2: Point the CNAME record of [SUB-DOMAIN] to lnk.pepipost.net
Once you are done with the above steps, please send an email to firstname.lastname@example.org with your username and sub-domain. Our delivery team will enable the custom envelope/return path address and DKIM for your account.
Note: Generally, this process takes 24-48 hrs of time frame, but in case you didn’t receive a reply from us within the said timeframe, then you can directly reach us over live chat.