This article provides a good overview of the process with pictures: https://spinbackup.com/blog/how-to-import-mbox-to-gmail/
To complete this process, you will need:
- the password to your personal mailbox (@gmail.com, etc.)
- the password to the @brown.edu mailbox
- a standalone (free) mail managing software, such as Thunderbird: https://www.thunderbird.net/en-US/
- the "ImportExportTools NG" add-on to Thunderbird
Once ready, the following steps will need to be taken to move mail into an @brown.edu account.
- Obtain a .mbox file of the mail you want to transfer. When using an @gmail.com account, the easiest way to do this is by going to https://takeout.google.com and following the steps to export an archive of the files from your @gmail.com account. Those files will export as .zip files, which can then be opened to find the .mbox (mail) file.
- Open Thunderbird and add your @brown.edu email account to the system. It will ask for the password once in a normal text box, then again in a Google pop-up box.
- Create a new folder within your @brown.edu mailbox to hold the imported mail
- Under the Tools menu, select the ImportExportTools NG option to import the .mbox file
- Select the .mbox file you extracted from the old personal email account
- Wait for the transfer to complete. It is best if you have a solid internet with good upload speeds and avoid the Brown VPN while completing this process.
When that process is done, the old mail will be in your @brown.edu account and accessible for use.