folders which are numerical names

if your folder is a primary directly under $MAILPATH/ it works fine, as a
pure numeric

so folder +2021 is fine -and I do this for archives by year.

if your folder is sub-folder under another folder like +sent/2021 it only
kind-of works. Any function which performs scan functions looks to pure
numeric objects as files, and barfs on the directory. So I work around it
by having archives like sent/y2021 and it works fine.

the other path out here is to do folder +2021/sent and subfolder sent
inside the archive year which works fine.

I just wondered if a stat() on the object to skip (sub)folders in contexts
which demand files would work? Might be a pain to implement without
unwanted side-effects.

-G