Exporter for Outlook is an application for macOS. It provides a simple series of steps, that will help you transfer all the contents from your Outlook for Mac, into other programs and file formats.
Exporter for Outlook will talk directly with Outlook for Mac (both versions 2011 and 2016), and extract all its information. There are multiple export options, depending on the item type:
Messages
Messages can be exported in MBOX or EML format. In both cases, the folder hierarchy is maintained. If your intention is to import messages into Apple Mail, select MBOX as the output format. When you finish, simply open Apple Mail and select the File option, Import and pick "Import from mbox files". When prompted, select the folder you used during the export process.
Contacts
Contacts in Outlook can be transferred directly to the Contacts app in you Mac, or if you prefer, you can save contacts as separate VCARD files (.vcf). The direct transfer is faster and more simple. However, if you intend to merge the exported items, with existing contacts, you may use the vcard option instead. You may later import the vcf files into Contacts, and the application will detect duplicates and prompt you what you would like to do with these special cases.
Appointments
Appointments from Outlook can be transferred automatically into the Calendar app in your Mac. However, if you prefer, you may export each appointment into an .ics file. This is a standard format understood by most calendar applications.
Notes
Notes can be transferred directly to the Notes app in your Mac. You may also export notes as mbox files, in case you would like to import them into a mail program
Tasks
Tasks in Outlook are transferred directly into the Reminder app in your Mac. Alternatively, you may also export tasks as .ics files.