I'm currently creating a newsletter template in InDesign but when I tried to export it to HTML, everything got messed up (layout, pictures, alignment...).
How can I fix it? Could you please help me?
InDesign's HTML export is not intended to give you an end product, just something to work with. If you want HTML that's properly formatted with CSS and JS you'll need in5.
>> I'm currently creating a newsletter template in InDesign
All modern email-software have it some html-template features. Why do you want it to use here InDesign?
You're not going to get the results you want straight out of InDesign. If you create custom CSS for the HTML, it is possible.
Another option is to publish the document using Publish Online (which you already have, so no extra cost), which creates a URL for your doc. You can include all of InDesign's interactive features. Some great examples here: http://bit.ly/PubOnCollection
External link in an email looks like spam. Publish online isn't helpful here.
Of course, Publish Online may not be the solution. But just want to clarify that the link in the email can say anything, it doesn't have to be the URL. E.g., Click HERE, that sort of thing. It is true that the URL, once the page is viewed, is that long, enigmatic indd.adobe.com URL.