Sadly, I am returning this tool. There is no way to remove the branding, even when buying 3 or more codes. It is a no-go for me.
I briefly tested, emails didn't arrive to my gmail, but that could be something I missed or that it took longer. I did not test extensively to see why.
The tool looks amazing if you are ok with their branding.
I tested plain emails, those don't seem to have the branding, but unfortunately, there are no line breaks either.