You send a large file by using Microsoft Office Communicator 2007 R2 and a Microsoft Office Communications Server (OCS) server that has the Microsoft Forefront Security for Office Communications Server (FSOCS) component installed. In this situation, you may receive the following error message after one minute:
"Cannot send <filename> to <username>".
However, if you keep the file transfer instant messaging (IM) session open, the recipient can eventually receive the large file from you.