If I just type 'email encoder' into the Search Plugins box in order to add a new plugin I get an error message saying 'Forbidden - You don't have permission to access /wp-admin/plugin-install.php on this server.'
I've tried entering the search term 'email' and then scrolling down the list till I find this plugin and when I select it I get the same message.
I'm able to add other plugins.
Can you think of an explanation why this might be? Conflict with another plugin? My hunch is that for some reason the plugin has been 'blacklisted' even at the search level by my webhost (the incredibly restrictive one.com – the subject of several complaints on google...).
I do have a couple of other WordPress sites, one of which is hosted on one.com. I could install the plugin on each of those to narrow down the problem, if you think I should give one.com the benefit of the doubt...