gnus-article-update-date-headers

gnus-article-update-date-headers is a variable defined in `gnus-art.el'.
Its value is

nil

Documentation:
A number that says how often to update the date header (in seconds).
If nil, don't update it at all.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.