Quality of images when publishing HTML pages through Word

I am trying to make a mailing list, using the mail merge AND the HTML editor
of WORD. The problem is, that all images I include in the message, look
awfull when I send the email! What does Word do with the images for web pages?

Why my document is not the same, but simmilar, when I see in the "Web Page
Preview" and in the outlook message? My outlook is configured to send and
receive HTML messages, and actually the message done in WORD arrived in HTML,
but the tables arrived absolutelly unformated. Are there any tutorial,
teaching how to make HTML email using the WORD?