Moving Mail from Physics to G.Harvard or Office 365
NOTE: The Physics mail server will become 'forward-only' on January 9th. Your Physics address should forward to another address by then and any mail remaining on the Physics server should be moved to another account before that date. Your Physics address will continue to forward to your other address after that date, but no longer store or send mail.
The best method for moving mail from one email account to another is to use an email client (presumably the one you intend to use from here on) and set up both both email accounts on it (as IMAP accounts). You can then drag and drop individual messages or whole folders from one location to another. Any modern email client (including Thunderbird, Apple Mail and Outlook) will allow you to set up multiple accounts and move mail between them. This method means you will not need to convert message formats and the date, time and that read status of message can generally be maintained.
Set your Physics address to forward to your @fas, @g.harvard.edu or other account here: Set Forwarding
The settings for configuring Physics mail (using the IMAP protocol) can be found at: https://mail.physics.harvard.edu/settings
It is important that you use IMAP when setting up the Physics account, and not POP3, as A) we don't support POP3 and B) IMAP will preserve the dates and times of messages when moved from on account to the other. POP3 would deliver all messages as new and unread and you do not want that.
Once you've configured your email client to access both accounts, you can then simply drag and drop individual messages, multiple selected messages or entire folders from one account to the other letting IMAP handle all the details. Keep in mind that moving large chunks of messages or large folders will take time and for very large folders you may want to do it in smaller chunks. But, in the end, you will have cleanly moved your mail and kept time stamps and other important information intact.