what is notify-send (Ubuntu)

I am try to use Thunderbird of my Email client. but I found the notify time is too short when a new message coming. so I try to modify it....
the notify-send !
This was pretty cool , Wanted to share with you all !!!!

Notify-send is a great application for notifying you when an event has occurred. An event such as a script running to completion.

If notify-send is not installed on your machine already, install the package "libnotify1" (or possibly just "libnotify") and  "libnotify-bin" from your repositories.

Once installed you can simply type the following, at the command line, to display a pop-up message near your system tray:

Code:

notify-send "hello"

By default the message will be displayed for 5 seconds. To change how long a message stays displayed use the "-t" switch. This will change, in milliseconds, how long the message is displayed. Enter "-t 0" to leave the message up until the user closes it.

Code:

notify-send "This message will be displayed for 3 seconds" -t 3000
notify-send "Click me to close me." -t 0

You can even add a title and an icon to the notification.

Code:

notify-send "This is the Title" /
            "Check out the cool icon" /
            -i /usr/share/pixmaps/gnome-terminal.png

When used in a script you could set it to notify you periodically by placing the command in a loop:

Code:

#!/bin/bash

while [ 1 ]; do
     notify-send "Up Time" "`uptime`"
     sleep 5m
done