Mac mail POP to IMAP problems

HI all,

I've recently decided to change one of my email accounts from POP to IMAP (I will also do that soon on my iphone & macbook air so i can have all emails coming in & out saved on all devices.. as soon as i sort this issue out)

I followed the instructions on how to do the setup from my web hosting company & had little trouble, except for when i hit the step that tells you to move all the old emails from the POP account inbox over to the new IMAP account inbox before deleting the POP account altogether.. (otherwise apparently you will lose those old emails).

When i dragged them all over to the IMAP inbox I noticed that rather than them appearing there, suddenly all 700 old emails were routed to the outgoing email folder & being sent.. somewhere.. I clicked cancel & then noticed they were no longer in either inbox.. Now I am stumped as to where they are

The few that made it through the process of being sent outgoing (before i clicked cancel) were redownloaded in both the IMAP & POPs inbox so they were definitely being emailed which i find strange.. Anyway, how do i get all my old emails into the new IMAP inbox please???

I assume they are now in my sent folder.. or at worst in a time machine backup..