Philip Guenther suggested to Mike Harris,
| Since the default mailbox has an absolute path, changing MAILDIR won't
| affect delivery to $DEFAULT.
Make that "If" instead of "Since".
Changing MAILDIR will affect $DEFAULT if you have redefined DEFAULT as a
relative path or as a simple basename. If you don't want the value of
DEFAULT to follow along with changes to $MAILDIR, then be careful to use a
full absolute path (or variables that expand to a full absolute path) when
you assign DEFAULT.
The same applies to ORGMAIL, though I'd consider it risky ever to assign
a relative path or a simple basename to $ORGMAIL.
I have situations where I intentionally set DEFAULT to a simple basename
and then let changes to MAILDIR carry $DEFAULT along, and they work as I
described.
[Yes, it can be argued that a simple basename is a special case of the idea
of a relative path, but I felt it safer to state both, even if some of you
consider the result redundant.]