I want to create the following situation. I have 2 ftp users who should be able to read each other's files and directories but won't be able to delete / edit except their own files and directories.

I think this should be done with the sticky bit but how can i setup that when a user creates a directory it automatically has sticky bit on?

I tried the following in the proftpd.conf, but this doesn't work.
Umask 022 1002
Umask 022 01002
(The directory created now has permissions 775 now but no sticky bit, so it is still possible that they delete / edit each other's files.)

Now i'm trying mod_exec but don't understand how setup "chmod after each mkdir"    Does anybody know if this is even possible..?