A method and system for file transfer are provided in which a file is transferred between a source client and a destination client via a middle server. The server receives segments of a file from the source client and stores the segments of the file as they are received. The server also forwards the segments of the file to a destination client as they are received, with the exception of one segment. The server combines the segments to form the whole file and applies a process to the whole file. The process may be for example an authorisation process such as an anti-virus check, a confidentiality check, or a content validity check. If the file passes the process, the remaining excepted segment is forwarded to the destination client.