[IMAP] An attempt to connect to failed.
This is my log:

16:32:47 Online state: changed to online due to NetworkAvailability
16:32:47 [IMAP]  Synchronizing subfolders: For folder
16:32:53 [IMAP]  Synchronizing subfolders: Done
16:32:53 [IMAP]  Synchronizing messages: For folder
16:32:54 [IMAP]  Synchronizing messages: For folder
16:32:56 [IMAP]  MailClient.Accounts.ConnectionException:
16:32:56 ()
16:32:56    at MailClient.Protocols.Imap.Synchronizer.ImapCommand.ThrowIfConnectionBroken(BasicResponse response)
16:32:56    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)
16:32:56    at MailClient.Protocols.Imap.Synchronizer.SynchronizeMessagesCommand.ExecuteInternal(WorkerStatus status)
16:32:56    at MailClient.Protocols.Imap.Synchronizer.ImapCommand.Execute(WorkerStatus status)
16:32:56    at MailClient.Commands.Command.Process(WorkerStatus status)

And it is for more than 3 days. The account setings are ok. And I can see Bulk mails and Junk mails. What should I do?

It might just be a problem with Yahoo. Did you contact their support to find out?

A good place to gauge what is going on with that company is at DownDetector.

I guess my link did not paste.

No, it is not a problem with Yahoo. I can login on yahoo with webmail.

It is not a problem with Yahoo web mail interface. That is a different thing entirely.

It could be a problem with Yahoo IMAP/SMTP/POP3 servers. Please contact Yahoo support, or check DownDetector and see if others are having the same problem.

Well … it seems that I can log in with IMAP from my smartphone. But Yahoo is saying that there are some problems with IMAP connection.