see this:
support.sparkpost.com
how do i do that with Mailwizz? I need to be able to specify the bounce domain via the API in order for Sparkpost to not use their default domain in the Return-Path.
Custom Bounce Domains
You can improve your deliverability and email branding by adding a custom bounce domain A custom bounce domain provides another layer to the branding that some ISPs care about.
support.sparkpost.com
how do i do that with Mailwizz? I need to be able to specify the bounce domain via the API in order for Sparkpost to not use their default domain in the Return-Path.