Just a thought as I posted this a long time ago,

I need to be able to disable FTP accounts for certain users as some of them have Mail only accounts.

Would manually changing the users shell to a false path have any implications to their mail accounts? as this should adequately stop them from logging in to their FTP accounts (only discovered through experimentation on a debian test box - users with their shell set wrong couldnt log into the server via proftpd)

I am not by any means a linux expert so I was hoping someone like chirpy or dgbaker could enlighten me as to whether or not this will work and what the implications of doing this are?