If I put <xen: include get an error and if I put <xen: require template is saved does not work.
I do not know if this is a bug or a not implementing feature.
If it is a not implementing feature, please, take this as a request to that effect, but if this is a bug, please a solution.
I created an addon and I tried to include a template to work with css style properties without success.
It would be great to work with style properties in email templates.