will wrote:

Hello,

I have set up a box which will act as our Mail-Server.

How should I set up the permissions for user which only are allowed to use mail on this System. (Sending by SMTP getting via popper)

Which shell should I give them?

/bin/false should do it.

Which would be the best home-directory?

give them a real home. This may be empty - but makes it possible to have the mail file on different servers (mounting /home/username via autofs) if later desired. But you may give them all one empty home if you like, leaving mail where it resides normaly (/var/spool/mail). -- Thomas