mh-expand-file-name

mh-expand-file-name is an autoloaded Lisp function in `mh-utils.el'.

(mh-expand-file-name FILENAME &optional DEFAULT)

Expand FILENAME like `expand-file-name', but also handle MH folder names.
Any filename that starts with '+' is treated as a folder name.
See `expand-file-name' for description of DEFAULT.