The MIT distribution of hesiod supports the hes_getmailhost(3) call for looking up a user's post office. If your site is running MIT's hesiod, you should define this. If you are running DEC's hesiod, you should not:

APPENDDEF(`confENVDEF', `-DHES_GETMAILHOST')

HES_GETMAILHOST is, by default, not defined. If you need it, you must define it in your Build m4 file.

If you are running a precompiled sendmail binary, you can use the -d0.1 debugging command-line switch (-d0.1) to determine if HES_GETMAILHOST support is included (if it appears in the list, support is included).