gnus-treat-strip-list-identifiers

gnus-treat-strip-list-identifiers is a variable defined in `gnus-art.el'.
Its value is

head

Documentation:
Strip list identifiers from `gnus-list-identifiers`.
Valid values are nil, t, `head', `first', `last', an integer or a
predicate. See Info node `(gnus)Customizing Articles'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.