stable --icedove --esr
$ cat /etc/apt/sources.list | grep "deb http://security.debian.org/ wheezy/updates main"
$ sudo apt-get update
$ sudo apt-get install icedove
stable --icedove --esr
$ cat /etc/apt/sources.list | grep "deb http://security.debian.org/ wheezy/updates main"
$ sudo apt-get update
$ sudo apt-get install icedove