The confUBINOWN macro determines the ownership of user-executable files. This macro assigns its value to the BINOWN= Makefile directive, but only for the following programs: editmap, mailstats, makemap, praliases, rmail, vacation, and smrsh. This macro is usually correctly defined for you in your devtools/OS file. To change the ownership of these programs, you might do this:

define(`confUBINOWN', `sendmail')

Note that the newaliases, mailq, hoststat, and purgestat programs are really symbolic links, so the concept of ownership does not apply.