What is a mail robot?

Several things that can be done with such a system:

Database query

The message contains a query in a more or less formal language; the mail robot will answer it after a (maybe very time-consuming) query of both local and remote databases; actually, the database can be off-line (i.e.: not always accessible: in this case the robot will queue the requests until the server will be ready);

Data entry

The message contains data to be inserted or updated into a database; a good application is a seller that fills in order forms on a portable PC and then transmits all the orders via mail at hte end of the day;

Automatic answer

When a user is on vacation, it is possible to leave a robot that answers his/her mail with a message like

  I'm away.
  I'll return on xx.yy.zzzz and then I'll answer your mail.
  Cheers

Message filtering

All the incoming messages can be processed and classified into several folders; unwanted advertisements can be throwed away without the need for downloading it.

Remote control

if you leave a computer in charge of controlling the house or a factory, you can address to it a message for, as an example, telling to it when you will return from holidays and so when it will have to raise the heating.