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)

Hello,
please try the latest version of eM Client - http://www.emclient.com/dist/v7.0.27804/setup.msi and let me know if the issue persists.

Regards,
Olivia

I am using the latest version and the same issue occurs.

thanks.

Hello,
can you add eM Client to exceptions in your firewall and antivirus software and see if that solves the issue?

Regards,
Olivia

I turned off firewall and av software but it does not solve the issue.

It seems like that em Client has a bug after fetching mails from server.
I captured IMAP packets and there was no error message. (I’m not sure. I scanned IMAP protocol briefly)

Hello,
seems like a server issue then, can you contact your mail provider if they have any issue with this connection or at least acquire server-side logs?

Regards,
Olivia