You can send mail to other users in the same system and receive mail from them by using the mailx commands. If two UNIX systems are connected in a network and can ping, Telnet, and ftp to each other, then users on the system can usually send mail to users on the other system using the same mailx command. If your system is connected to the Internet, then you can use mailx to send mail to anyone in the world and receive replies.
Alternatives to mailx
mailx is an older, character-based mail program that cannot handle email attachments. UNIX programs such as pine or elm can be easier to use on character-based terminals. A Windows PC can be used to pop waiting mail from a UNIX system for a particular user, and then the mail ...