gnus-diary provides new sorting functions (see Sorting the Summary Buffer ) called gnus-summary-sort-by-schedule,
gnus-thread-sort-by-schedule and
gnus-article-sort-by-schedule. These functions let you organize
your diary summary buffers from the closest event to the farthest one.
gnus-diary automatically installs
gnus-summary-sort-by-schedule as a menu item in the summary
buffer’s “sort” menu, and the two others as the primary (hence
default) sorting functions in the group parameters (see Diary Group Parameters).