In the Swaarm's Partner Platform, your publisher can create and manager their own postback easily. Here is a quick guide on where this is located:

Global Postback in Partner Platform

Go to the Partner Platform by clicking Quick Links > Partner Platform on any Publisher details page. (Your publisher would simply login to the partner platform)
Go to Settings
Click Postback Links Tab
Click Create Postback Link and enter a Postback
Click save and the Postback is ready to go.

Offer Specific Postback

On the Partner Platform, go to the Offers Page and select a specific Running Offer you want to create/manage a postback.
Scroll to the bottom and click the Postback Links tab.
Here you can set a postback for a specific event on CPA campaigns.
Click Save.

This is to enable your publishers to set their postbacks and edit when needed.
The update or change will reflect immediately in both Partner Platform and Swaarm if either you or your Publisher makes a change.
Check off the box "Receive only postbacks with a payout greater than zero" if they only want to receive paid postbacks.
Popular Postback Macros are there to make it easier for your Publisher to copy and paste without having to look it up or type out the macro, removing room for error.
You can view your Publisher Postback in Swaarm under their Publisher Details Page > Postback Links tab.
Remember to give your Publisher's access to the Partner Platform under their Publisher Details Page > Contacts and entering their email as well as checking off the box Partner System Access.