Two or more objects have the same mail address, and mail is sent to that address. The duplicated e-mail address may be an ...

{4}: Two or more objects have the same mail address, and mail is sent to that address. The duplicated e-mail address may be an SMTP or non-SMTP address. This is usually caused by a configuration problem of Active Directory. Modify the affected recipient directory object to have a unique e-mail address and resend the message.