What is Object Program?

Object Programs are programs in machine language form. Normally users write computer program using high level languages or assembly languages. If program is written in high level language, then it is to get converted to machine executable form using a Compiler. If program is prepared in assembly language, it is usually to be converted to machine executable form using an assembler. Output of compiler or even assemblers are called object program. They can be directly accomplished by machine.

What is Message Transfer Agent?

The other subsystem of e-mail system is message transfer agent. It actions messages from source to vacation spot. They are system programs that run from the background and move e-mail with the system. They establish a transport connection in the source machine to destination machine and transfer the message.

What is Mail Box?

Mail box could be a provision in e-mail system to store incoming e-mail. Users will actually examine the contents of mail boxes and delete messages via mail boxes.