empty mailbox deletion and /bin/mail forwarding bug

[Tony L. Hansen]

< But wait - there's more!
<   At least one of the replacement mailers will:
<   (A) allow forwarding to programs when "|command" is found in the
<       forwarding file.
<   (B) run the program under the uid of the recipient of the message.
<   (C) perform a security check before doing (B), based on the ownership
<       of the forwarding file.

The SVr4 mail program gets it right. It does the right thing in setting up
mailboxes, setting up forwarding (including forwarding to |command), and does
it all with chown() enabled on the system.

					Tony Hansen
				att!pegasus!hansen, attmail!tony
				    hansen at pegasus.att.com