in creating html emails you have think way retro and stick to the KISS principle in layout and styling.
css support varies greatly in email clients and html emails is the 1 place where I would say it is ok to use tables for layout.
try to keep style specifications to font and colours and not much more in order to minimise the risk of the message content breaking in the email client.
a couple of tips.
1) send both a html and plain text version of the content in the one email to the recipient.
2) include a link to a web based version of the content in the email.