You should be able to configure Pine to check any IMAP account. By default it logs in with your shell username but you can set it to use other login information, such as your m____ account. You might even able able to set up multiple accounts at once but I have never seen that done.
And as for your original question, I believe that Purge in Outlook is equivalent to Expunge in other IMAP clients. The IMAP way of deleting items is to flag them as deleted and leave them in their current mailbox. Many mail clients use a different scheme where they use a Trash folder on the server and move messages to the Trash folder instead of deleting them in place.
IMAP’s native deletion process is a two-stage delete, like most systems. First you flag messages as deleted, and then you send an expunge command to the server which actually throws away the messages which are flagged as deleted. I believe Outlook follows this structure, rather than using a separate trash mailbox. So when you delete an item, it stays in the box but disappears from view, or depending on your display settings it might stay in your mailbox view but have a strikethrough on the text, indicating the deletion status. The purge command purges (expunges) all the deleted messages from the server.
It may be that you can set Outlook to behave differently, but I use it very rarely so I don’t really know how.