Transferring Dartmouth Mailbox to A Personal Mailbox
Dartmouth’s email service does not support POP or IMAP, so the only way to bulk-export your emails is with a desktop email application. Apple Mail and Outlook 2016 are options (the online version of Outlook will not work).
You will need to connect both your personal account and your Dartmouth account to your chosen email client and then move or copy emails between accounts.
Instructions are available on the ITC Service Portal page: Leaving Dartmouth -- Export Email and Contacts to Gmail