When mail is sent using the command line or sendmail -v, mail is sent
correctly.

When netscape connects to sendmail over localhost, all messages are
queued, but never sent until one runs sendmail -q, at which point they
are properly sent on their way.

When

      FEATURE(`accept_unresolvable_domains')

is commented out, the problem disappears.

When one connects to sendmail via port 25, and runs commands by hand,
when one gives the RCPT myname@anothermachine.domain.name command,
it responds that the recipient is ok, and then "will queue".

When the feature (?) is turned off, then everything works as it should (at
least
as I expect it should -- mail is sent).

It is as if it hasn't yet check to see if it can resolve the recipient
domain when the
message is accepted and queued for later delivery, yet if the message is
not accepted
at this point, sendmail goes on to find that the domain can in fact be
resolved and
all is well.