Even if it can't set the PTR it's self, it could at least detect if your PTR is missing or wrong, and display that information to you with some advice on how to resolve it and how important it is.
https://github.com/JoshData/mailinabox/commit/ec11241a7a619a...
* Test/alert if your PTR mismatches your HELO name
* If your IP is on any of the major RBLs
* Point admins toward AOL/Yahoo/ReturnPath whitelists and feedback loops.