If you want to use the messaging indicator in Xubuntu 13.04 (Raring Ringtail) are only these few steps necessary:

Download messagingmenu@mozilla.com.xpi and install it in thunderbird (remove "/usr/lib/thunderbird-addons/extensions/messagingmenu@mozilla.com.xpi" first).
Afterwards execute these commands in a root shell:


echo "deb http://packages.s7t.de/ubuntu raring main" >> /etc/apt/sources.list
apt-get update
apt-get install indicator-messages indicator-messages-gtk2 indicator-status-provider-emesene indicator-status-provider-mc5 indicator-status-provider-pidgin indicator-status-provider-telepathy libindicator-messages-status-provider1 libindicator-messages-status-provider-dev pidgin-libnotify