jje, Geoff: To make sure the script keeps running after you lose your connection to the server, you can run it in a screen session. Google the term for more information.
stergos: Unfortunately, we can't set up an erro page specifically for this issue. The technical reasons behind its occurrence are the same as the reasons behind why queued accounts show it - it's a case where the name server has the domain on record, but the web server does not.