We are a company based in Oman. We are running MS exchange 2003 with windows 2003 server operating system. We are facing a problem since last week with the synchronization. Some of the user are not able to synchronize the e-mails to the server the below message is displayed. " 16:56:09 Synchronizing Mailbox 'username' 16:56:09 Synchronizing Hierarchy 16:56:10 Synchronizing Favorites 16:56:10 Synchronizing Folder 'Inbox' 16:56:51 Error synchronizing folder 16:56:51 [80004005-501-50B-550] 16:56:51 The client operation failed. 16:56:51 Microsoft Exchange Server Information Store 16:56:51 For more information on this failure, click the URL below: 16:56:51 http://www.microsoft.com/support/prodredirect/outlook2000_us.asp?err=800 04005-501-50b-550 16:56:51 Canceled 16:56:52 Microsoft Exchange offline address book 16:56:52 Download successful " I would appreciate you help in this issue. Regards, Suleiman Almantheri IT Help Desk Oman Oil Company Tel : +968 573100 Fax :+968 567386 This email is confidential and may also be privileged. If you are not the intended recipient please notify the Company's IT Department immediately by telephoning +968 573100. You should not copy it or use it for any purpose nor disclose its contents to any other person.