How may I recover the disk space used by a deleted local folder? Apparently the space is still consumed in a large mail_data.dat file, despite that the program did an auto-check.
Background.
I ran an .mbox import to a new local folder which failed:
possibly due to disc space shortage, and the program closed itself. I reopened, and after completion of the auto-check, found the new folder containing less than the .mbox’s message qty, and deleted it. Checking free disc space, I found no reduction.