[Exim] 4xx on low disk space

Is there a way to make exim return a 4xx error when low disk space is
encountered? I have looked through the documentation and I don't see a
way to set Exim (using 4.14) to refuse mail when disk space is below
xxKB or anything of the like. Is there a way? If not, can we request it
be added to the next exim release?

Thanks!

--- Dan