# TODO
* list footer
* append to plain text single part
* or add a plain text (or HTML?) part if multi-part
* how do we deal with signed messages?
* list headers
* RFC 2919 `List-Id: $name <$post-address=~s/@/./>`
* RFC 2396
* `List-Help: <mailto:$admin>` (if can `->admin`)
* `List-Owner: <mailto:$admin>` (if can `->admin`)
* `List-Unsubscribe: <mailto:$unsub_address>` (if we can (un)subscribe)
* `List-Subscribe: <mailto:$sub_address>` (if we can (un)subscribe)
* `List-Post: <mailto:$post_address>`
* `List-Archive: NO` (configurable)
* subject [tag]
* test what happens with mime-word-encoded subjects!
* reply-to munging
* set `Reply-to` to list's post address (return path)
