put signature into an attachment

Hi, first of all I would like to say that you guys are doing a great job.

However, there's one feature that I miss a lot, it's the possibility to put the signature of the mail into an attachment, and not in the body of the mail as it is done in the actual version. I used to sign each mail I was sending when I used a "real" mail client, but now that I try to use only the webmail, it's impossible (you can't place an "in body" pgp signature when sending a mail to a mailing list, it's ugly).

I know it's a planned feature, but when will it come ?

Thanks for the great job.