[Evolution] Character set not supported by Internet?

["Steven P. Auerbach" <STEVEN P AUERBACH saic com>]

Lately I've gotten a few complaints from recipients of email I sent
using Evolution 2.0.3. They get a message which is copied below:

> This message uses a character set that is not supported by the Internet
> Service.  To view the original message content,  open the attached message.
> If the text doesn't display correctly, save the attachment to disk, and then
> open it using a viewer that can display the original character set. 
>  <<message.txt>> 

They are using Outlook. My message (at least in the most recent case)
had some quoted text which was from an email I received from someone
else, which I inserted using "Paste Quotation", i.e. shift-control-V.

What's going on here? How do I avoid this?
Steve
-- 
Steven P. Auerbach <steven p auerbach saic com>