Hey Steven,,,,

"All email messages are standard text files. Some mail clients combine those files into a single file (Outlook on Windows does this), but some keep the individual files separately. (I think Outlook on Mac works this way.)

(Yes, even mail messages with formatting and pictures, videos, etc are encoded as 7-bit text files.)"

Well, that is not exactly true, in T-Bird you have a global Option to send as Plain-Text or as HTML, or both, and you can also control the sending format via your Address-Book, so that it is recipient, dependent!!!

Also, how T-Bird stores your Data:

http://dotwhat.net/msf/227/

"The .msf extension (Mail Summary File) is used by Mozilla's Thunderbird email client. Thunderbird stores the user's mail in two files, one without an extension (E.g Inbox) which holds the actual mail messages in the standard 'mbox' format and the other with an .msf extension (E.g Inbox.msf) which holds an index of the mail.
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To convert Thunderbird emails (mbox format) to eml files (used by Microsoft Outlook and Microsoft's Outlook Express), you will need a tool such as IMAPSize:

http://www.broobles.com/imapsize/th2outlook.php

Here is an example from my T-bird Inbox, as Opened and viewed by WordPad:

--bcaec54ee9103fc95404d357702e
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div><font size=3D"4"><strong><u>Clubhouse Internet</u></strong></font></di=
v><div><font size=3D"4">Internet at the Clubhouse is now up and running.=A0=
=A0=A0</font></div><div><font size=3D"4"></font>=A0</div><div><font size=3D=
"4"><u><strong>Variety Show</strong></u></font></div>
<div><font size=3D"4">If you are thinking of taking part in the "Secon=
d Annual" Variety Show you are urged to sign up in the MM Clubhouse as=
soon as possible.=A0 There will be a meeting of all those who plan on taki=
ng part in this fun show next Tuesday, January 21st.=A0 The show will take =
place on Friday, February 1, 2013, at 7 PM <u>provided we have enough parti=
cipants</u>.=A0 We need to know how many are thinking of taking part.=A0 If=
we don't have enough participants, we may decide to cancel the show.=
=A0 Please sign up as soon as possible!=A0 Glen Dukes, Coordinator</font></=
div>
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Just my 2 cents worth,,,

TK...