I'm not sure if this is a problem from Newsletter Subscribe Mod or in zencart.

But my HTML emails have an &addr= line instead of &addr=

I am not sure how to fix it, I can not find where the & comes from since it it built through the templates and functions. The rest of the text seems to be fine with correct encoded & - just not the unsubscribe link.

Also HTML emails lack DOCTYPE.

Regular TEXT emails use & and that is okay.