A host with insecure FTP and alphanumeric usernames

I know this is a very odd question, but a particular service I'm working with requires an FTP account to push data to me via FTP through port 21 using an alphanumeric username. The only host I've been able to find which supports insecure FTP (lunarpages) uses FTP usernames of the format 'x@y.z'. Does anyone know of a service which offers this? It's not exactly information they print in the pitch.

Since it's just a test, I'd prefer shared hosting, but honestly I'd settle for anything short of a dedicated server by now.

Cheers, Wyatt