I have an account that previously had email forwarded to an external (home) email account. Instead of removing the delivery options from the user account and then removing the contact in AD, the contact was erased first. Now whenever someone sends her an email she gets a system admin message:
Your message did not reach some or all of the intended recipients.
"The email account does not exist at the organization this message was send to. Check the email address, or contact the recipient directly to find out the correct address.
What to do?