You‘re changing jobs—either voluntarily or not so—and IT‘s going to shut off your access to your old email , contacts, and calendars. While they may consider all of this company property (and I suppose it is), the truth is that many people often mix in personal email with their company stuff.
The upshot is that you‘d like to make copies of this before it vanishes. How do you do it? Let‘s start with Mail.
The trick to grabbing your old email is making an archive of your selected inbox or account. In this case, I have a bunch of mail stored in Mail’s inbox for a Google account that I’ll say is my work email account. To make an archive of it I just select Export Mailbox from the Mailbox menu. (Or I can just right-click on my inbox and choose this same command).
http://www.macworld.com/article/2882619/archive-your-email-contacts-and-calendars-before-its-too-late.html