Problems transferring email from local folders to new imap server
Changed our email server from POP to IMAP. Set up account Ok. Getting/sending emails Ok. Need to move prior emails from local folders to new IMAP acct. If I drag and drop a small folder (15-20 emails) it seems to work Ok. But if I drag/drop folder with 400 emails (some with large attachments) the process hangs up and does not finish. Some of the emails being moved are duplicated several times in the destination. My solution for now appears to be moving 5-10 emails at a time. Emails with large attachments are moved one at a time. This process is time consuming and error prone. Computer Win10.
Opaite Mbohovái (1)
I think you have run into one of the limitations of IMAP, it is not a file service, so it is not designed with large uploads in mind. Disabling your anti virus program from scanning mail (they are mails) and preventing it from scanning your profile folder will improve the situation. But it will not cure it.