Drag and drop e-mail backup

Hello, I'm a quite experienced computer user, and there's one thing I would like to ask, because I couldn't figure it out myself.
I didn't found anything that allowed to do an e-mail backup by drag and drop, just like you could do with normal pc folders.
I know that Thunderbird's or Outlook's incoming mail folders are not real folders, but I don't think it would be too difficult to implement such a thing - like a "save all" style function. You're forced to save each single message, losing a lot of time if you want single copies and don't want to keep backup .msf, ."" and stuff files and folders.
Think I made it clear.
I use Thunderbird: if there's a method, please let me know
Thank you for you kindness and patience in reading
Paolo

 

Apparently, there's a bugzilla report, but it only has some 14 votes since 2004...
https://bugzilla.mozilla.org/show_bug.cgi?id=227305
A workaround here:
http://nic-nac-project.de/~kaosmos/mboximport-en.html
That's just incredible. It should be on top of the agenda... If I had more time to spare I would code it myself.
Bye

 

This feature is available in Outlook since years. Not only 2007 (AFAIK).
Then, why don't I use Outlook?
Ehe... good question...
just list some:
1) outlook isn't free (but o. express is)
2) outlook uses (AFAIK) more system resources
3) the outlook I used to use screwed up every 5 minutes
4) ...
bye