A ~/.forward file must be owned by the user or
by root. If it is not, it is considered unsafe,
and sendmail ignores it. The
-d27.4 debugging switch causes
sendmail to print a message describing any such
file it finds unsafe:
include: not safe (uid=user-id)
Note that a file is considered unsafe if, among other things, it
lacks all read permissions.
The -d27.4 debugging switch also causes
sendmail to print information about a
:include: file beyond that printed with
-d27.2:
include(file) 
printed with -d27.2
ruid=real-user-ideuid=effective-user-idprinted with -d27.4
This shows the real user-id (the
ruid=) and effective user-id
(the euid=) of the current running
sendmail.
The -d27.4 debugging switch causes
sendmail to print an error if a
:include: or ~/.forward file
cannot be opened for reading:
include: open: reason here
