Making Outlook email templates is a pain because of the html support offered there. You have to have styles embedded, all images need to be remotely referenced (not in a folder under the code pages, which is what Xara tries to create but can't put into Outlook). HTML Tables are best in this case for any layout that has to go past basic 1 column, and I HATE HTML tables.

As sledger indicated - don't waste your time trying to make this work. Mailchimp is a great system and they have worked out all the layout bugs for you for many of the mail clients (Outlook, Live Mail, Gmail, etc). You can certainly use graphics from your Xara application for the design elements to bring your branding/colors in. Like everything, it takes a bit of work, but once you create the "template" there, you can reuse it for future mailings.

Hope that adds something.