Office 365 - Apple Mail - Export Autofill/Autocomplete
This document will provide guidance on how to export Autofill/Autocomplete contacts' addresses from Apple Mail to a new machine, whether it be a MacBook, iPad, or iPhone. This will allow the user to automatically autofill/populate an email address when composing a new email that is being sent to a previous contact. A list of email addresses can not be extracted from Apple Mail. However you can add email addresses from your Previous Recipients to your contacts.
Open Apple Mail.
Click Window and then click Previous Recipients.
Choose which email addresses you wish to move to your contacts and click Add to Contacts.