sendmail gethostbyaddr fails

[Mike Pfleger <pfleger@pfleger-precision.com>]

Hello.

I am getting a slew of entries in /var/log/mail/mail.warn that
look like this:

Jul 13 10:20:01 BananaSlug sm-msp-queue[1116]: gethostbyaddr(192.168.1.45) failed: 1
Jul 13 10:30:01 BananaSlug sm-msp-queue[1150]: gethostbyaddr(192.168.1.45) failed: 1
Jul 13 10:40:01 BananaSlug sm-msp-queue[1175]: gethostbyaddr(192.168.1.45) failed: 1
Jul 13 10:50:02 BananaSlug sm-msp-queue[1206]: gethostbyaddr(192.168.1.45) failed: 1
Jul 13 11:00:02 BananaSlug sm-msp-queue[1244]: gethostbyaddr(192.168.1.45) failed: 1
Jul 13 11:10:02 BananaSlug sm-msp-queue[1268]: gethostbyaddr(192.168.1.45) failed: 1

They happen every 10 mins, which is the polling interval for the
sendmail daemon.  Has anyone seen this?  Is this a misconfigured
sendmail thing, or is there some DHCP issue here?  An interesting
note is that the address seems to increment by one with each reboot.
I shut off every night to let some of the heat dissipate from my
apartment, and to allow me to sleep w/o the roar of the fans...

Thanks in advance,
Mike