Upgrade ur Exchange 5.5 service pack to at least sp 4. This problem can occur if there is an error in the way the MTA processes its internal control blocks. U might also find this URL very useful. http://support.microsoft.com/search/preview.aspx?scid=kb;en-us;Q266792 Tony McCarthy wrote:http://www.MSExchange.org/ Hi Everyone, I'm getting the following error message (below) in my event log on a Win2K server running Exchange 5.5. I've got no idea what this is about however I've had a few syncing problems with this server, i.e. some users have complained that their mailboxes sync with the Exchange server slowly and sometimes abort the sync. Any ideas?? Regards Tony Event Type: Warning Event Source: MSExchangeMTA Event Category: Interface Event ID: 4283 Date: 7/12/2002 Time: 6:34:52 AM User: N/A Computer: SYDNEY2 Description: Unable to recognize an internal message identifier. Internal connection handle (LPI) 1-15-1 Error code: 8464 [POP4 POP4 UP 8 228] (14) ------------------------------------------------------ You are currently subscribed to this MSExchange.org Discussion List as: hoppy_lumz@xxxxxxxxx To unsubscribe send a blank email to $subst('Email.Unsub') --------------------------------- Do You Yahoo!? New! SBC Yahoo! Dial - 1st Month Free & unlimited access