There are many mail clients available for Unix. These include mutt, fetchmail, getmail, and pine.
Pine is a third-party software package that does not come with Unix or Linux; it has to be installed. It was written for a beginner in mind so that they didn't have to know a lot about the Unix environment when using mail. Mailx is a standard Unix mail client that is typically supplied with a Unix install. It is somewhat easy to use but requires the user to know how to use an editor such as 'vi' and to use somewhat arcane means of answering mail.
Not sure what you mean by enter a file; you could use an editor, such as vi, emacs, nano, pine, etc. to edit it.
UUCP is the abbriviation of Unix to Unix copy. It is worldwide email system called UUCP or Unix to Unix copy.This email system was developed for the operating system called Unix.
No, but Linux is based on Unix since Linux is a Unix clone.
Unix work is performed by users of the unix system, for application and system programs, or anything that requires a Unix system.
A computer that runs Unix.
Unix commands
A Unix console is a CLI interface through which to control or monitor a Unix computer.
Unix configuration is the process of tailoring a freshly installed version of Unix to your particular environment. Each Unix system may do that differently.
Solaris is a specific version of Unix; the term 'Unix' refers to a classification, and several vendors provide a Unix-like environment. So, in a sense, Unix and Solaris are the same thing.
There is no "default" Unix shell. Different Unix vendors shipped different shells.