I have sendmail-8.12.8-9.90 setup at the mail server on my LAN. I have noticed some error messages it the /var/log/maillog lately but I don't understand what the messages mean. Sometimes when I send mail through the server, I have noticed that about several "timeout waiting for input from local during Draining Input" messages appear but the email is still delivered. What do these messages mean?

I have also noticed "DSN: unknown mailer error 243" errors. What does that mean?

Here is a sample of my /var/log/maillog:

Jul 14 11:05:28 logger sendmail[9571]: i6EI4LpQ009565: to=<bell@here.com>, delay=00:00:59, xdelay=00:00:19, mailer=esmtp, pri=30483, relay=mail01.here.com. [65.113.241.100], dsn=2.0.0, stat=Sent (
Message received OK)
Jul 14 11:05:30 logger sendmail[9549]: i6EI2Ypa009484: timeout waiting for input from local during Draining Input
Jul 14 11:05:32 logger sendmail[9545]: i6EI2YpZ009484: timeout waiting for input from local during Draining Input
Jul 14 11:05:36 logger sendmail[9535]: i6EI2YpY009484: timeout waiting for input from local during Draining Input
Jul 14 11:05:39 logger sendmail[9528]: i6EI2YpX009484: timeout waiting for input from local during Draining Input
Jul 14 11:05:43 logger sendmail[9553]: i6EI2Ypb009484: timeout waiting for input from local during Draining Input
Jul 14 11:05:57 logger sendmail[9557]: i6EI2Ypc009484: timeout waiting for input from local during Draining Input
Jul 14 11:06:04 logger sendmail[9561]: i6EI2Ypd009484: timeout waiting for input from local during Draining Input
Jul 14 11:06:08 logger sendmail[9561]: i6EI2Ypd009484: to=andrewstrmail, delay=00:02:30, xdelay=00:02:08, mailer=local, pri=142463, dsn=2.0.0, stat=Sent
Jul 14 11:06:17 logger sendmail[9557]: i6EI2Ypc009484: to=andrewstrmail, delay=00:02:52, xdelay=00:02:29, mailer=local, pri=31576, dsn=2.0.0, stat=Sent
Jul 14 11:06:32 logger sendmail[9502]: i6EI2YpU009484: to=andrewstrmail, delay=00:03:52, xdelay=00:03:49, mailer=local, pri=141150, dsn=5.3.0, stat=unknown mailer error 243
Jul 14 11:06:40 logger sendmail[9566]: i6EI2Ype009484: to=andrewstrmail, delay=00:02:50, xdelay=00:02:05, mailer=local, pri=142443, dsn=2.0.0, stat=Sent
Jul 14 11:06:41 logger sendmail[9502]: i6EI2YpU009484: i6EI6apQ009502: DSN: unknown mailer error 243