IMAP does not sync well

I was using outlook and I imported accounts from outlook.
one of accounts has problem in syncing

eM Client syncs well sometimes(10%), but rest of that it fails.

I attach log
오후 4:15:02 ***@hanyang.ac.kr [IMAP]  MailClient.Accounts.ConnectionException: 오후 4:15:02 (Connection terminated)
오후 4:15:02    at MailClient.Protocols.Imap.Synchronizer.ImapCommand.ThrowIfConnectionBroken(BasicResponse response)
오후 4:15:02    at MailClient.Protocols.Imap.Synchronizer.SynchronizeMessagesCommand.FetchNewMessages(ConnectionContext context, String selectPath, UInt32 idLow, UInt32 idHigh, String idList, Boolean useUid, UInt32 messageCountEstimate, Boolean newestFirst, Boolean breakOnNewMessages)
오후 4:15:02    at MailClient.Protocols.Imap.Synchronizer.SynchronizeMessagesCommand.ExecuteInternal(WorkerStatus status)
오후 4:15:02    at MailClient.Protocols.Imap.Synchronizer.ImapCommand.Execute(WorkerStatus status)
오후 4:15:02    at MailClient.Commands.Command.Process(WorkerStatus status)