If your webmail system has the Archive plugin installed, a button labelled Archive appears in the toolbar email task. This button moves the selected message(s) to the archive folder with one single click.

You can configure how the archive folder is organized and divided into subfolders either by date, sender or originating folder.

Note: 

In order to activate the archiving functions you first need to select a folder as archive in the Preferences > Special Folders settings.