virtualmin sendmail dontblamesendmail valid shell and forwarding

I’m running FC4 with the latest version of sendmail, proftpd, webmin, usermin and virtualmin.
Recently, I discovered that my autoreply.pl script no longer worked. After a lot of investigation, this is what I found.
I needed to set the “O DontBlameSendmail=GroupWritableDirPathSafe” in sendmail.cf
I had to give all users a valid shell.

Now mail, and mail forwarding with autoreply seem to work great. However, this seems to have broken my proftpd setup, where before I had seperated ftp users from non ftp users by a valid vs an invalid shell. Now because all users have a valid shell, proftpd lets all users have ftp access.

Help in this matter would be greatly appreciated.
Thanks,
D. Babcock