How do I transfer my UMBC email to a personal Gmail account?

In a clean browser (i.e. close your web browser window(s) and open a new one with only the 1 tab open) login to your UMBC Gmail by navigating to https://gmail.umbc.edu and logging in.
In that same browser window navigate to https://takeout.google.com to download your Google content from your UMBC account.
Select the data you want to export (i.e. Contacts to just export your contacts, or Gmail to export all the data in your mailbox). All content is selected by default, this can be very large and time consuming to download. Ensure you click on the box near the top of the center pane Deselect all and then only select the items you want to export.
Click on “Next Step” at the bottom of the page. The Type and Destination page will load.
In the Choose Type and Destination page select how you would like to receive this data. A link sent to your UMBC email address is the default and is usually appropriate. Other destination options (i.e. One Drive) will require you to provide credentials for that service to Google.
Click on “Create Export” at the bottom of the page. Once the export is complete a link we be emailed to you (or the data will be sent to the external service selected above).
Use the link to download the data (or download it from the service you specified above).

You now have a local copy of the Google data that you selected from your UMBC Google account. You can use tools provided by your new email provider to upload that data into your new email account or various 3rd party applications that are available online. Note: UMBC DoIT does not endorse or support any particular application for this purpose and cannot assist you with the data upload to another email provider once you have obtained your data via Google takeout.

Additional information on Google Takeout can be found here: https://support.google.com/accounts/answer/3024190?hl=en

Information on importing MBOX formatted mailboxes into GMail can be found here:
https://support.google.com/mail/thread/3296831/how-can-i-import-mbox-file-of-old-email-from-another-account-into-gmail-account?hl=en

The following article provides additional information:
https://spin.ai/blog/how-to-import-mbox-to-gmail/