mailx is a Unix utility program for sending and receiving mail, also known as a Mail User Agent program. Being a console application with a command syntax similar to ed, it is the POSIX standardized variant of the Berkeley Mail utility.
mailx– Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group
- History of mail and mailx from the Heirloom Project
- mailx Tutorial from the engineering Dpt. at Purdue University
- mail at GNU Mailutils manual
- S-nail mailx(1) manual