How to imbed images in an email?

[Josef Lowder]

I do not use HTML for email (either to send or receive), but I still 
occasionally get some email messages that have graphics and images 
imbedded. How is that done? 

Sometimes I would like to be able to send an embedded image, too. 
How can that be done with Thunderbird and/or with Kmail? It seems 
that sometimes when I send an attachment it shows up in the body 
of the message and sometimes it is only available as an attachment.