Attempts to route mail to @sina.com crash the server

We are finding that messages addressed to users with the sina.com domain are causing the server to crash, and continue to crash on restart until a new copy of mail.box is created.

I have no idea why this might be happening, and the Notes log does not show any information. Any idea where else I can look? Our server is hosted by Prominic, so I’m not sure if I have (easy) access to any RIP or other dump files.

Any advice or assistance would be greatly appreciated.