At irregular intervals, emails from various users are not reaching recipient. Following is the error message: Your message did not reach some or all of the intended recipients. The following recipient(s) could not be reached: john on 8/24/07 2:45 PM The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator. The MTS-ID of the original message is: c=US;a=;p=Company;l=MERC-0708-2728 Please help if you know how to correct this. Thanks in advance. KT

Where is those mails sent, To Internet or internal users

The addresses that are unable to deliver are Internet/external addresses. The email has both internal and Internet but the Internet is the only part that doesn't work. Thanks KT

Okay, this issue happens on Internal and Internet emails. Just had one bounce back that was to someone internally. Thanks

How are users ubmitting mail. MAPI or SMTP

SMTP

I suspect user error. Are you positive that they send to correct SMTP address are the bouncing mails new mails or replies

That was my first thought as well but then I went to the user PC and use the Tools/ resend email and it worked fine.

I was migrating from Exchange 5.5 to Exchange 2003. Once I turned off the 5.5 exchange server this corrected itself. KT