[mlmmj] Thunderbird behaviour with Reply-To header

Hello,

For my mailing lists I prefer to have the address of the mailing list 
instead of the original poster. This makes easier contributions for 
people not used to mailing list which only use "Reply" instead of Reply 
All or Reply List.

I've tried to add Reply-To as custom header with the mailing list.

When sending a mail to the list, I get the original post (fine), hitting 
the simple "Reply" button makes thunderbird answering twice:

     To: thelist@thedomain
     Reply-To: thelist@thedomain

Without the Reply-To header, clicking the Reply button makes thunderbird 
answering the original poster and not the mailing list address.

It looks like it's the only mail application doing that but I wonder if 
I should add more settings or use something else?

What's your thoughts on it?

Regards

-- 
David Demelier