Currently there is no built-in method of mass-actioning articles beyond the checkboxes seen when managing articles in the control panel. This allows you to action up to 20 items at a time.
You may however increase the amount of articles which are shown on one page by a small customisation. Please note that this customisation is not officially supported, and increasing this number too high may cause your pages to take a long time to load.
In file /lib/common.defines.php, near line 109, find the following:
define("AL_ARTICLES_PER_PAGE", 20);
And change the number 20 to another, larger number - such as 200 or 1000. Example:
define("AL_ARTICLES_PER_PAGE", 200);
This will increase the number of articles that load, per-page, in your control panel. Allowing you to perform checkbox actions over more of them at once.
Other values for news, comments and blogs can also be found near this line in the same file and can be adjusted similarly.
Once you have performed the actions required it's recommended that you adjust this back to the original value to maintain control panel performance.
