In jetpack/modules/contact-form/grunion-contact-form.php at line 958 in trunk, the plugin automatically sets the From address to be wordpress@ the site's domain. However, in pluggable.php the www. part of a domain is removed if it exists.
It would be nice if Jetpack was consistent with WordPress (or in fact, simply left WordPress to do the work, thus allowing plugins to filter jetpack emails also). Where can I file such a request / bug report?
Love & joy - Callum.