Comment 5 for bug 544898

The part for receiving mail is done, see revision 637 in my ~ulm/vm/experimental branch. There are two new boolean variables vm-honor-mail-followup-to and vm-honor-mail-reply-to.

I'm not completely sure how to control behaviour when sending. Would something like the following be reasonable, to be implemented in vm-mail-internal:

  - If vm-honor-mail-followup-to is non-nil,
    and the "To" address is found in a list of subscribed mailing lists
    (follow thunderbird and call it vm-subscribed-mailing-lists?)
    then add a MFT header containing the "To" address.

  - If vm-honor-mail-reply-to is non-nil,
    and the "To" address is found in vm-reply-ignored-reply-tos,
    then add a MRT header containing:
      - the address from mail-default-reply-to (if it exists),
        or the vm-mail-header-from address.

Should the vm-reply-ignored-reply-tos variable be reused here, or should we introduce yet another custom variable (vm-reply-to-mangling-mailing-lists?). VM already suffers from having too many custom variables.