Image size not taken into account for mass contact...

Hi!
I am trying to add images in the mass contact form.
I am using cck.
I chose "Image", then into the images properties, I pasted this url http://www.netpublic.fr/wp-content/uploads/2010/09/facebook.png and in width I chose 30 px.
However, when I try to send a mass mail, the widht of the image is the original one (311 px) and not the one I chose instead (30px)
I checked "Send as HTML.
The message will be sent using the Full HTML input format"
Can anybody tell me what is wrong ?
Thanks in advance!!!