Well I went home and you are all correct, sendmail is built to use hash.

However the sendmail.cf file that comes with NetBSD 1.4.2 has dbm instead of
hash.

Now for the most part this isn't a problem since all the places that have
dbm are remarked out.

So the short answer to a long questions is:

1) sendmail stock 1.4.2 and in the pkgsrc uses hash not dbm (not a problem,
I've got it working now!)
2) The sendmail.cf file in 1.4.2 is in error having dbm instead of hash as a
class, which would classify it as a bug.

So I'll send a PR.

Cheers and thanks!

jam