While the MAIL facility is supported on MPE/iX, it is not
as effective as other types of IPC, for several reasons:
Communication can take place only between processes in the same process tree. Communication between processes in different trees is not possible using MAIL.
Each pair of processes requires a separate "mailbox" to transfer messages between them. This is a less efficient use of system storage than in other forms of IPC.
Only upward and downward (parent/child) communication is possible. Communication between sibling processes is not.
For these reasons, it is preferable to use other forms of IPC when generating new applications on MPE/iX. Use variables for simple IPC within jobs and sessions; use the file system features to perform IPC between different jobs and sessions in a network.
