mh-alias-completion-ignore-case-flag

mh-alias-completion-ignore-case-flag is a variable defined in `mh-e.el'.
Its value is

t

Documentation:
*Non-nil means don't consider case significant in MH alias completion.

As MH ignores case in the aliases, so too does MH-E. However, you
may turn off this option to make case significant which can be
used to segregate completion of your aliases. You might use
lowercase for mailing lists and uppercase for people.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 7.1 of the MH-E package that is part of Emacs 22.1.