Rmail/mbox new mail/coding system issue

[Paul Michael Reilly]

Currently, Rmail (and Pmail) append new mail messages to the current
mail buffer.  With Rmail/mbox the mail buffer is unibyte.  But since
the User can select new mail to come from a non-mbox mail file
(especially a collection of Babyl formatted messages) it is now pretty
clear to me that Rmail/mbox must read the new mail messages into a
temporary buffer (with multibyte enabled) where the collection is
converted, if necessary, to mbox format and then appended to the
Rmail/mbox collection of messages.

The issue is how to handle the per-message encoding that might be
necessary to represent the message in a unibyte buffer.  Off the top
of my head I would be inclined to encode the message as base64 but I
would not be surprised if that is overly simplistic.

First, how can I tell if a message must be encoded?

Second, I confess to not knowing Babyl sufficiently well to know if it
loses information in the process of decoding and storing the messages.
So, is it even possible to re-encode a Babyl message?

Are there any other issues with getting new mail into an Rmail/mbox
buffer that I have not identified?

Thanks,

-pmr