There is no default for MAILFROM. However, Infoprint Server always includes userid@domainname to identify the sender. userid is the TSO user ID of the job submitter and domainname is the domain name where Infoprint Server is running. For example, if someone with a TSO user ID of JOHN sends an e-mail, and Infoprint Server is running on domain SYSTEM1, Infoprint Server will include JOHN@SYSTEM1.