Missing email when moved between folders

I have a Macbook Air. I am using the macmail for multiple email accounts. I fixed issues with the IMAP set up on one of the accounts that did not create properly when the email account was loaded. It created 2 sent folders one called "Sent" and another called "Sent Messages" open the sent messages folder and highlighted all the email 161 emails and dragged them over to the "Sent" folder. After a while we came back to check them and they were all gone. not showing up in the "Sent Messages" folder not the "Sent" folder. Where are they?