To confirm it is Lightning Box. Still free for lightning address if desired
Discussion
In which version of the app is this feature?
I havent updated my blixt for awhile but it Should be in most recent version too.
Someone said in the comments this might be an iOS limitation. I’m running the most recent testflight version 0.6.9 (83)
Ah it very well could be; I'm running on android.
Lightning Box is at the bottom in advanced settings, once you open the top left drop down menu on initial launch page.
Hope its there for you.