Mail for macOS Sierra: Import or export mailboxes

https://support.apple.com/kb/PH22318?locale=en_US


Export items to an archive file in Outlook for Mac

https://support.office.com/en-us/article/Export-items-to-an-archive-file-in-Outlook-for-Mac-281A62BF-CC42-46B1-9AD5-6BDA80CA3106

http://www.cumc.columbia.edu/it/howto/email/bulkmac.html


Migrating to Office365:

https://docs.microsoft.com/en-us/Exchange/mailbox-migration/migrating-imap-mailboxes/migrating-imap-mailboxes?redirectSourcePath=%252fen-us%252farticle%252fWhat-you-need-to-know-about-migrating-your-IMAP-mailboxes-to-Office-365-3fe19996-29bc-4879-aab9-5a622b2f1481


https://expert-advice.org/microsoft-outlook/manually-convert-olm-file-pst-format-olm-pst-conversion/


Mac OLM to PST:

https://www.nucleustechnologies.com/olm-to-pst.html

https://www.stellarinfo.com/gdc/olm-to-pst-converter.php?gclid=Cj0KEQjw7dfKBRCdkKrvmfKtyeoBEiQAch0egTFOi8w_xsE4k4g-YeWmqhfW8sVOXNM7qApfLmStE0AaArii8P8HAQ

http://applemailtopst.com/how-to-convert-apple-mail-database-to-pst-directly-on-mac/