[Alpine-info] Alpine-generated message in forwarded mail not seen in Outlook

[Brad Chamberlain via Alpine-info]

Hello everyone —

This week I was informed of a strange behavior that was previously unknown 
to me, concerning reading mails I'd written in alpine from Outlook, and I 
wanted to pass it along to see whether it was familiar to anyone else.

First, in case it matters, my SMTP server is:

 	smtp.office365.com/user=my.email at hostname.com/submit/auth=xoauth2

The situation was that I was forwarding a mail from a colleague whose 
parts/attachments list was as follows:

    1                       Multipart/RELATED
    1.1 Shown   ~135 lines  Text (charset: ISO-8859-1)
    1.2   OK     8.5 KB     Image, "image001.png"
    2     OK      12 MB     Application, "filename.pptx"

In forwarding the mail from alpine, I wrote my own introduction to it, 
providing context.  The attachment list for that sent mail, as seen in my 
sent-mail folder, was:

    1   Shown     51 lines  Text
    2                       Multipart/RELATED
    2.1 Shown   ~135 lines  Text (charset: ISO-8859-1)
    2.2   OK     8.5 KB     Image, "image001.png"
    3     OK      12 MB     Application, "filename.pptx"

However, when my colleagues viewed the mail in Outlook (our default mail 
client) or I viewed the same mail in my own sent-mail folder in Outlook, 
the message I had attached was not visible, neither in preview mode, nor 
when double-cliecking to open the message.

Forwarding the same mail in the same way to Gmail worked as expected, and 
unsurprisingly, the mail also renders fine from within alpine.  That is, 
my new message was visible by default.

This now makes me curious whether I've been hit by this other times in the 
past without anyone noticing.  In this case we only noticed because the 
person asked a question I told them I'd answered in the original mail, 
only to learn that they never saw it.  Going back further in my sent-mail 
folder for other forwarded case, however, it seems I do not forward mails 
very often.  The only other one I found in the past six months was all 
Text/PLAIN and seems to render fine when viewed in Outlook.

Thanks for any information here,
-Brad