Addresses missing from mail group
I have created a mail group, but when I send a message, two of the emails get omitted. They appear in the group in the Contacts app, but when I expand the list in the email address bar, they are missing. i can manually add them, and they will get the message, so I don't think there is a problem with either my address or theirs.
iMac with Retina 5K display, iOS 8.4