How can I disable threading in some (e.g., mail-) groups, or set other variables specific for some groups?
While in group buffer move point over the group and hit
G c, this opens a buffer where you
can set options for the group. At the bottom of the buffer
you’ll find an item that allows you to set variables
locally for the group. To disable threading enter
gnus-show-threads as name of variable and nil as
value. Hit button done at the top of the buffer when
you’re ready.