gnus-parameters-case-fold-search

gnus-parameters-case-fold-search is a variable defined in `gnus.el'.
Its value is

default

Documentation:
If it is t, ignore case of group names specified in `gnus-parameters'.
If it is nil, don't ignore case. If it is `default', which is for the
backward compatibility, use the value of `case-fold-search'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.