Variable: gnus-refer-thread-limit
gnus-refer-thread-limit is a customizable variable defined in
gnus-sum.el.gz.
Value
500
Documentation
The number of old headers to fetch when doing A T (gnus-summary-refer-thread).
If t, fetch all the available old headers.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/gnus-sum.el.gz
(defcustom gnus-refer-thread-limit 500
"The number of old headers to fetch when doing \\<gnus-summary-mode-map>\\[gnus-summary-refer-thread].
If t, fetch all the available old headers."
:group 'gnus-thread
:type '(choice number
(sexp :menu-tag "other" t)))