LinuxQuestions.org - Sendmail 8.13.8 not delivering, logfile says otherwise

Hello,

I am very confused. I have a MediaWiki server set up to send verification mail to a user when he/she signs up for a new user account. I have verified that the sendmail daemon on the same server is able to send mail by sending a test mail from webmin to my gmail account. When the MediaWiki sends the mail, the message never reaches my gmail account. I have checked /var/mail.log, and it reports that the mail has been sent properly, just like the other test mail I sent. Here are the contents of /var/mail.log:

May 16 21:50:16 whiteboy sendmail[7969]: gethostbyaddr(192.168.1.100) failed: 1
May 16 21:53:19 whiteboy sendmail[8020]: l4H4r9Hr008020: from=epitome@whiteboy, size=439, class=0, nrcpts=1, msgid=<1179377589.8018@whiteboy>, relay=root@localhost
May 16 21:53:29 whiteboy sm-mta[8022]: l4H4rJKB008022: from=<epitome@whiteboy.epitos.org>, size=585, class=0, nrcpts=1, msgid=<1179377589.8018@whiteboy>, proto=ESMTP, daemon=MSP-v4, relay=localhost [127.0.0.1]
May 16 21:53:29 whiteboy sendmail[8020]: l4H4r9Hr008020: to=craigmjackson@gmail.com, ctladdr=epitome@whiteboy (1000/1000), delay=00:00:20, xdelay=00:00:10, mailer=relay, pri=30439, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l4H4rJKB008022 Message accepted for delivery)
May 16 21:54:09 whiteboy sm-mta[8024]: l4H4rJKB008022: to=<craigmjackson@gmail.com>, ctladdr=<epitome@whiteboy.epitos.org> (1000/1000), delay=00:00:39, xdelay=00:00:39, mailer=esmtp, pri=120585, relay=gmail-smtp-in.l.google.com. [72.14.253.27], dsn=2.0.0, stat=Sent (OK 1179377650 n20si144428pof)
May 16 21:55:17 whiteboy sendmail[8058]: gethostbyaddr(192.168.1.100) failed: 1
May 16 22:11:59 whiteboy sendmail[8198]: l4H5Bnea008198: from=www-data, size=673, class=0, nrcpts=1, msgid=<200705170511.l4H5Bnea008198@whiteboy.epitos.org>, relay=www-data@localhost
May 16 22:12:09 whiteboy sm-mta[8199]: l4H5BxRa008199: from=<www-data@whiteboy.epitos.org>, size=908, class=0, nrcpts=1, msgid=<200705170511.l4H5Bnea008198@whiteboy.epitos.org>, proto=ESMTP, daemon=MSP-v4, relay=localhost [127.0.0.1]
May 16 22:12:09 whiteboy sendmail[8198]: l4H5Bnea008198: to=Testuser <craigmjackson@gmail.com>, ctladdr=www-data (33/33), delay=00:00:20, xdelay=00:00:10, mailer=relay, pri=30673, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l4H5BxRa008199 Message accepted for delivery)
May 16 22:12:32 whiteboy sm-mta[8202]: l4H5BxRa008199: to=<craigmjackson@gmail.com>, ctladdr=<www-data@whiteboy.epitos.org> (33/33), delay=00:00:23, xdelay=00:00:23, mailer=esmtp, pri=120908, relay=gmail-smtp-in.l.google.com. [72.14.253.27], dsn=2.0.0, stat=Sent (OK 1179378753 z20si208328pod)
May 16 22:17:20 whiteboy sendmail[8223]: l4H5HAAC008223: from=www-data, size=673, class=0, nrcpts=1, msgid=<200705170517.l4H5HAAC008223@whiteboy.epitos.org>, relay=www-data@localhost
May 16 22:17:30 whiteboy sm-mta[8225]: l4H5HKJf008225: from=<www-data@whiteboy.epitos.org>, size=908, class=0, nrcpts=1, msgid=<200705170517.l4H5HAAC008223@whiteboy.epitos.org>, proto=ESMTP, daemon=MSP-v4, relay=localhost [127.0.0.1]
May 16 22:17:30 whiteboy sendmail[8223]: l4H5HAAC008223: to=Testuser <craigmjackson@gmail.com>, ctladdr=www-data (33/33), delay=00:00:20, xdelay=00:00:10, mailer=relay, pri=30673, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (l4H5HKJf008225 Message accepted for delivery)
May 16 22:18:16 whiteboy sm-mta[8228]: l4H5HKJf008225: to=<craigmjackson@gmail.com>, ctladdr=<www-data@whiteboy.epitos.org> (33/33), delay=00:00:46, xdelay=00:00:46, mailer=esmtp, pri=120908, relay=alt2.gmail-smtp-in.l.google.com. [66.249.83.27], dsn=2.0.0, stat=Sent (OK 1179379097 h37si242780wxd)
May 16 22:44:30 whiteboy sendmail[8378]: gethostbyaddr(192.168.1.100) failed: 1
May 16 22:50:56 whiteboy sendmail[8413]: gethostbyaddr(192.168.1.100) failed: 1

Do these gethostbyaddr errors ring a bell for anyone? Or is this a MediaWiki-specific issue?

Thank you,

Craig Jackson
craigmjackson@gmail.com