I've done quite a bit of searching on this topic and have found somewhat relevant information on issues that seem similar to the issue I'm having.. but like I said, they seemed similar.
Anyways: User submits order, everything goes well - user receives invoice email, administrator receives email, etc etc. Now user wants another copy of the invoice email so I go to Store Administration > Orders > View orders > [pick ANY order and view it] > Click "Invoice" tab > Click "Mail invoice" sub-tab >
Now the page comes up just fine, email is already there : I click the "Mail invoice" button and I get "Page not found", and the email does NOT get sent.
I find this very odd as everything else seems to work just fine. I've poked around in the settings and have NO IDEA what's causing this, and I don't even know where to start..
All help is appreciated! 
