Hello Donncha,
We have a WP 3.2.1 running on nginx. All works well.
However, if we switch to the mapped domain names as the primary domains both wp_mail and mail stop working.
Any idea why?
They work well, if the blogs are running in the conventional (ie not mapped) mode.
Thank you.
L.
http://wordpress.org/extend/plugins/wordpress-mu-domain-mapping/