Fix the sync with the Mac OSX Address Book (Contacts)
You really need to fix the synchronization with the Mac OSX Contacts app. The only way I can edit a group email is to create a new group and copy the email addresses to the new group, within Contacts. Airmail will not re-sync with an existing Contacts Group if I change a member, or if I pick a different email address other than the first one in the group member's card (if they have more than one email address). This is very annoying. I'm OK with Airmail's other limitations (i.e., limited search functions), but I cannot deal with it not handling group emails correctly.
Add command to add an address to the airmail address book, not just mac contacts, without sending an email to them. Some you do not want to add to contacts, but want to have available.
Kevin Blissett commented
The sync feature in Preferences > Advanced > Sync contacts works fine, but it would be preferable if this happened automagically and not just when I do it manually or entirely restart Airmail.