Copying between folders in mail account does not work

I have imap-email accounts with too many folders I have created. I wanted to reduce the folders' amount and move mails between folders. crtl-a selects all mail in a folder, then with the right click menu of the mouse copy or move etc. It just does not do that. Only a small amount of mails is transferred. Same with grab and move to the folder. I then tried to move the mails to a local folder, delete them and move them from the local folder to the destination. Same problem. They would not move to the local folder. Is there any configuration limiting the intended moves?