For the transfer of email from your physics account to, say your external mail account (google, yahoo, hotmail or other corporate email supporting imap) you will have to use an email application like Mozilla Thunderbird, Apple mail or Microsoft Outlook.
Set up both the physics account and your external account in the email application of your choice (Thunderbird, Outlook, Mail ...). For this you can find instructions in the document collection tagged email.
Having both emails setup in your email client you can drag and drop all your emails and any other folders you have created into your external mail client. Try not to move all the messages at once. Select batches of about 100 to 500 emails and copy them over. It is also safer to copy only one email folder at a time. You can try copying more at once but if you have tens of thousands of messages in your folder it would be better if you copied the folder one at a time.
After copying your emails to the external account, please make sure that you don't miss any emails or folders.