The -d44.5 debugging switch displays the values passed to sendmail's internal writable( ) routine. This routine nearly duplicates the function of the access(3) call^[6] but does it much more safely and allows checks to be made under the identity of the controlling user:

^[6] It is more restrictive for root-owned files and can allow the set-user-id semantics needed for delivery to files.

writable(fname, sff_flags) 

Here, the fname is the full pathname of the file being checked. The sff_flags are documented in Table 16-12 earlier. Success or failure is described under -d44.4.