Thank you Falko. Your advice was spot on. I shutdown sendmail and fired up postfix. My telnet results are now as expected.
220 kyleserver1.kylekarhohs.me ESMTP Postfix (Debian/GNU)
250-AUTH PLAIN LOGIN
221 2.0.0 Bye
Connection closed by foreign host.
However, my situation is still not completely resolved. I am able to send mail from within my RoundCube interface, but whenever I send an email to the address I get a 550 error.
I looked at the log, /var/log/mail.log, and found several things.
First, ClamAV kept recording that it was out of date. I saw the new ISPConfig updated ClamAV, so I went ahead and updated ISPConfig to version 2.2.32. My linux distro is Debian 5.0.1. Looking back in the log, ClamAV now confirms it is up to date.
Second, I do not know if this is normal, but my log is full of entries like this:
Apr 15 12:52:18 kyleserver1 imapd: LOGIN, user=username, ip=[::ffff:127.0.0.1], port=, protocol=IMAP
Apr 15 12:52:18 kyleserver1 imapd: LOGOUT, user=username, ip=[::ffff:127.0.0.1], headers=0, body=0, rcvd=10, sent=83, time=0
Apr 15 12:53:18 kyleserver1 imapd: Connection, ip=[::ffff:127.0.0.1]
Apr 15 12:53:18 kyleserver1 imapd: LOGIN, user=username, ip=[::ffff:127.0.0.1], port=, protocol=IMAP
Apr 15 12:53:18 kyleserver1 imapd: LOGOUT, user=username, ip=[::ffff:127.0.0.1], headers=0, body=0, rcvd=31, sent=335, time=0
90% of my log seems to be filled with the LOGIN-LOGOUT statements every minute. All that changes is the port number. Should there be one specific port number assigned to the mail?
Third, when I send an email from roundcube I can find the entry in the log that documents this action. However, there is no documentation of receiving an incoming message when I try to send an email to the account. It seems that whatever I am sending never makes it to the mail server. My mail log is becoming rather lengthy, too, is there a way to keep it short?
Thanks for your continued assistance Falko. Head way is being made, but might you know the cause of my latest quandry?