Hrm... I searched for sendmail 17152, and the most relevant thing I turned up was on a Majordomo page:
Mailer /usr/lib/sendmail exited unexpectedly with error 17152
This indicates an unsuccessful attempt to deliver email. This usually happens when one of the email addresses in your mailing list is incorrect. Look for the "To:" header in the bounced message, and make any needed corrections to your list using subscribe/unsubscribe