The -d27.9 debugging switch causes sendmail to trace the setting and resetting of its user-id and group-id identities when processing :include: and ~/.forward files. First, an additional line is printed below the output of the -d27.2 and -d27.4 debugging switches:

include(file)                          printed with -d27.2 
   ruid=real-user-id euid=effective-user-idprinted with -d27.4
include: old uid = real-user-id/effective-user-id 

The second and third lines contain the same information. After the new line is printed, sendmail might or might not change its identity depending on the nature of a :include: or ~/.forward file and that file's controlling user. Regardless of whether it changed, sendmail prints:

include: new uid = real-user-id/effective-user-id 

After sendmail has finished processing a :include: or ~/.forward file, it resets its user-id and group-id back to their original values and displays the result:

include: reset uid = real-user-id/effective-user-id