You will use autoresponders when you are
out of office. (an out of office reply message letting people know
that you are not available at present but will get back to them when
you are back. The autoresponder will automatically send a predefined
message that you have set up to anyone sending you a message.
It is also handy when you have potential clients
sending you a message, thanking them for their message and letting
them know that you are busy with their request and will get back to
them as soon as possible.
Many websites with memberships has this sending
an automated message to new members welcoming them.
Autoresponders can also be used to send a link to subscribers or banking details when a client places an order.