Add local system mail to mozilla thunderbird

	1) Install a Mail Transfer Agent (MTA)
		[emerge|pkg_add|aptitude|urpmi|rpm|yum|...] postfix	
	2) Go to your thunderbird profile directory into your local mail folder
		cd ~/.thunderbird/XXXXXXXX.default/Mail/Local\ Folders/		
		# XXXXXXX is random
	2) Create a symbolic link to your system mailmox
		ln -s /var/mail/USER system-mail		
		# where USER is your system username
		# and system-mail is the new mail sub-folder in thunderbird "LOCAL"

by Markus Sesser