HTML email guide -

I am not new to HTML / CSS, although I have never created an HTML email before.

Do I have to keep in mind when this email comes for the client?

Do they display different HTML / CSS content like browsers? (IE problems etc.)

I'm also not sure that HTML / CSS can be inserted! From 2008, there is a HTML Email Newsletters Guide. Some email templates can be found and in fact the old site's To mention why HTML email is bad, however, if you add an option for HTML email, then add one for plain text. I think I'm not the only one who likes plain text.