MH is a message handling system that provides a public-domain electronic mail system for UNIX. In contrast with the email system mail, MH is not a monolithic mail agent. A monolithic program is one that, when invoked, executes until terminated. A monolithic mail agent holds all its messages in one file. MH commands run from a shell prompt, which means that the user does not have to start or quit the mail agent. MH can take advantage of the power of the shell. Each message is stored in a separate file. Standard UNIX filesystem operations can be performed on the files. A front-end program, xmh, provides an interface to the MH commands. This front end provides a window and mouse interface in the X window system.

The book provides a detailed and comprehensive review of the features and functionality of MH and xmh. The audience is split between readers who want to be casual users of MH and xmh and those who want to be technical experts who can support the system for casual users. Even though the material necessary for the regular user is clearly identified, the book may overwhelm a user who has not previously been exposed to UNIX. Tutorial chapters called tours--one for MH and one for xmh--are helpful. Nevertheless, even though much of the material is not designed for average users, they may wish to take advantage of some of the other features as they gain more experience. The principal beneficiary of the book remains the expert, for whom it can serve as a useful reference. The book goes beyond reading, sending, finding, and organizing mail to how to customize MH and xmh and how to do shell programming with MH. Although the subject is technical, each topic is thoroughly covered, with examples clearly showing the use of each command.

The book contains a glossary and an index, both of which are essential for reference. A useful feature is an “MH Reference Guide,” printed on purple pages at the end of the book. All MH commands are listed with the available switches or parameters, a short description, and a reference to the section in the book where more information can be found.