Switching from Pop to iMap

So I tried to convert my mailbox for one of my personal e-mails from pop to iMap tonight, but failed miserably.

What I did was create a new account for the same e-mail address and this time set it up as iMap. I then pulled over everything from the old mailbox, to the new one.

I then proceded to delete the old account in Internet Accounts. When I went back into mail, the new folder was empty and all of my e-mails were gone.

I am now in the process of restoring my e-mail from Time Machine...

Any idea on how I can take a shot at this again? What I am trying to do is sync another e-mail address with my phone so e-mails show both up on both devices like my iCloud e-mail does.