Synch outlook.pst for POP account

I’ve got a user who uses a pop account instead of exchange for his outlook profile. I’m moving him to a new laptop and I’ve copied his .pst file over into outlook and set up the data files to use the old .pst file. It is a Yahoo plus account.
Whenever I open Outlook it starts to send every single(29,000) message that is in his Yahoo account. Is there a setting where it will only new messages from that day going forward?

Thanks