Hello, my Outlook 2003 user is getting these when he work with his calendar.

It is pointing to the Old mail user that they shared calendar in the past.
Please see message below.

I had run cleanserverrules command line, that did not fix the issue. Pleae
advise -
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From: System Administrator
Sent: Friday, October 05, 2007 11:09 AM
To:
Subject: Undeliverable: Accepted: xxxxxxxxxx

Your message did not reach some or all of the intended recipients.

Subject: Undeliverable: Accepted: xxxxxxxxxx
Sent: 10/5/2007 11:09 AM

The following recipient(s) could not be reached:

/O=OurCompany/OU=FIRST ADMINISTRATIVE
GROUP/CN=RECIPIENTS/CN=oldemailuser on 10/5/2007 11:09 AM
The e-mail account does not exist at the organization this
message was sent to. Check the e-mail address, or contact the recipient
directly to find out the correct address.
exchangeservername.company.com #5.1.1

-- TKM ----