Last week one of the users came to me saying he cant received emails from and external sender, wich was working before. setup is a SBS 2008 with Exchange 2007 all updates this is the message the sender is getting I have ask the sender to send email to other users with the same issue and error. the user are currently receiving emails from other senders and no issues. Thanks in advance for you suggestions GFX_03 _____________________________________________ From: System Administrator Sent: Thursday, November 17, 2011 2:26 PM To: XXXXX Subject: Undeliverable: XXXXXX and XXXXX Your message did not reach some or all of the intended recipients. Subject: FW: XXXXXXXX Sent: 11/17/2011 2:26 PM The following recipient(s) could not be reached: 'XXXXX@XXXXX.com' on 11/17/2011 2:26 PM 550 5.1.1 <XXXXX@XXXXX.com>... User unknown

Are you sure the external sender has the correct recipient address? Ask the, to test sending via OWA? Can you send to this internal recipient without issue? Can you send to the same user from google/hotmail, if yes, then the issue seem to be the external sender and not your Exch/user.Sukh

1) we tested sending from several users on there .net domain and there are all failing saying user unkown. when in fact the users and mail boxes due exist on the our domain, I will ask to see if they have this enable for the users 2) internally or externally no other users is having this behavior 3) we can send from other sources GMail, Yahoo no problem Note: the particular user has a BlackBerry and he can received the emails from our mail server with out any issues Thanks for the comments and suggestions, GFX_03

Ask the sender to use OWA and try sending a message, it seems like the issue is with the sender Org and not your.Sukh