Sounds a bit weird I know but after installing the SBS trial version of the email archiver product last week I tried to access the database with the search client at home through the corporate network over VPN and the application failed to find the database.
My next steps were to uninstall and reinstall everything on the client and server sides but to no effect (apart from the archive that I had started last week getting deleted). I got into the office this morning and behold a fully working search archive application.
Don't know if it is anything to do with database authentication over VPN but it is a bit weird.