Sendmail mail.local Failure

[KingFoobar at gmail.com]

For some reason, my local mailer is failing. I can send and receive to
remote servers just fine, but I can't transfer mail locally.

/var/log/maillog says:

sm-mta[31955]: starting daemon (8.14.1): SMTP+queueing at 00:30:00
sm-mta[31955]: started as: /usr/sbin/sendmail -L sm-mta -bd -q30m
sm-msp-queue[31959]: starting daemon (8.14.1): queueing at 00:30:00
sm-mta[31957]: l4CFZl3v031717: smtpquit: mailer local exited with exit value 1
sm-mta[31957]: l4CFZl3v031717: to=<my_user at my.domain.com>,
delay=00:50:00, xdelay=00:00:00, mailer=local, pri=241792,
relay=local, dsn=4.4.2, stat=Deferred: Connection reset by local

In my mc file, I have (Among other settings):

FEATURE(local_lmtp)
MAILER(local)
MAILER(smtp)

Why's the mail getting deferred?

I'm not on the mailing list, so please include me in any replies. Thanks!