Which version of Eudora?
I used to support 800 users of it on my own between 1995-1999 and it was a piece of cake to administer etc. Back then, each folder was kept as separate files with an index file IIRC (given that it was 10 yrs ago). Have not kept current with it though as Procomm started letting their marketing dept ruin what was a great product IMHO.