A system and method for performing efficient computer virus scanning of transient messages using checksums in a distributed computing environment is described. An incoming message is intercepted at a network domain boundary. The incoming message includes a body storing message content. The message content is parsed from the body and a checksum is calculated over the parsed message content. The checksum is stored in an information file associated with the incoming message in a transient message store. The incoming message is scanned for a presence of at least one of a computer virus and malware to identify infected message contents. The checksum corresponding to each infected message content and an infection indicator is recorded.