There are several reasons for my concern.
1. Disk space is limited on my CentOS server - I'll probably eventually have to use NSF to store the emails on a different server.
2. Disk space may be cheap but backup is not! The amount of emails you can backup is not determine by how much disk space you have but your backup media space.
3. If you don't set a quota, people will never learn how to manage their emails - as you pointed out, education is important!
OK - it seems I will just have to live without this 'feature' until some genius can come up with a patch for it.
Regards,
Mon