Had a former customer call a few (10) years ago, furious that we shut down their website.

Me: but you moved your website to another provider 2 years ago? We dont even provide webhosting any more?

Turns out, when they moved we put a redirect to their new site on our server.

During the summer this server was decommisoned due to a failing harddrive but since we no longer had any active customers on it we just pulled the plug.

The customer had never actually redirected their domain name. :)

When we sent them a copy of their own cancellation letter we got an "oh hell, sorry".

:D