Given that OS X Mail obviously recognizes all these recipients, you might think importing them should be easy. Good news: You’re right. You can harvest OS X Mail’s vast memory of all the people you have emailed to build your contact list in just a few steps.
Add Addresses From OS X Mail’s Auto-Complete List to the Address Book
To copy contact info from OS X Mail’s auto-complete list to its address book:
Select Window > Previous Recipients from the menu in OS X Mail. Highlight all desired addresses. You can highlight multiple addresses by holding down the Option key while clicking. Press Shift to select an address range. Click Add to Contacts (or Add to Address Book).
