|Title:||MH and xmh|
|Subtitle:||E-mail for users and programmers, Third edition|
|Publication date:||April 1995|
Besides the obvious, this book also covered the Tk application exmh. According to the publisher, this book has been discontinued, but has now been made available under the GPL on the web.
The original O'Reilly book it is at: http://www.oreilly.com/openbook/mh/
Updated editions are at
This link may be useful as well: MH-E Manual