Circles are also now supported in search and filters. Find messages from a specific circle by typing circle:[circle name] in the search box. You can also find mail from any of your circled contacts by searching with has:circle. You can refine your search even further with other criteria and create filters based on circles. This means you can now view all the unread emails from your ‘Friends’ circle or automatically star every message that comes from your ‘VIP’ circle. Itamar Gilad
Finally a meaningful way to use circles in your Gmail inbox! A little bit more automation for managing e-mail can’t hurt, for example a filter like this:
circle:friends subject:-(fw|fwd) ► Apply the label: Friends; Never send it to Spam
-has:circle ► Skip the Inbox (Archive it)
One can’t help wonder why this wasn’t doable with the plain old Groups in Contacts. Going through Google+ seems such an overkill.
I’m curios if this also applies to outgoing mail…