How o I create an enewsletter or ebulletin?

I want to send a regular monthly enewsletter out to clients. I have created it in Word and can do an email merge with a database (Access). The newsletter looks fantastic in Word and has quite a few graphics, hyperlinks etc in it to make it a visual impact. When it is received in Outlook in my dummy run it again looks good but when I try to view it through any webmail based application there are a lot of problems. Some text is fuzzy, some on top of other text, the graphics have jumped to where I don't expect and the links dont work? What am I doing wrong or is there a better way to do it? I am IT literate so please don't answer unless you really know what you are talking about.