And here is an example of what it looks like in the archives:
http://gerry.vanagon.com/cgi-bin/wa.exe?A2=ind2104d&L=vanagon&F=&S=&P=4998

On Tue, 27 Apr 2021 at 12:58, John Thiessen <john.thiessen@gmail.com> wrote:
>
> That's correct. All modern (current) email clients decode them on the
> fly and you never even know it.
>
> This issue exists because the server that archives the emails cannot
> decode Base64. This means you will never be able to search/ read the
> emails encoded with Base64 (such as Dennis' .. a real shame).
> Additionally, when the server accumulates a handful of emails and then
> issues them in digest mode, you will not be able to read those Base64
> emails (unless you manually decode each one of them)
>
> On Tue, 27 Apr 2021 at 12:49, Roy Nicholl <RNicholl@nbnet.nb.ca> wrote:
> >
> > I just had a look at the raw version of several of Dennis' posts (in elm, pine and Apple Mail) and all the ones I examined are base64 encoded which is pretty standard.
> >
> >
> > John Thiessen wrote on 2021.04.27 13:33:
> >
> > So we are getting somewhere ..  There was no problem in the past.
> > There now is a problem; certainly for some months now.
> >
> > The issue may be with a setting in Dennis' Hotmail account, OR, it
> > could be a setting in the email client that Dennis uses to send
> > emails.
> >
> > Note that there are other members where from time to time their emails
> > are also unreadable.
> >
> >
> >
> > On Tue, 27 Apr 2021 at 12:16, Dan N <dn92610@gmail.com> wrote:
> >
> > something must have happened on the List server related to Dennis' email address recently...
> >
> > here are one from him long ago (April/2017) and one from another person, both using Hotmail.com
> >
> >
> >
> >
> >