Connection error

I am getting a connection error, it was working and now it isn’t. Any idea how I can fix it?

Can you give the error which you will find in Menu > Tools > Operations > Log tab.

Please see examples of the error messages
09:18:21 MailClient.Accounts.AbortedException: Authentication aborted by user.
09:18:21    at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
09:18:21    at MailClient.Protocols.CalDav.Synchronizer.BootstrapCommand.UpdatePrincipalProperties(Uri baseUri, Boolean retryOnNotFound)
09:18:21    at MailClient.Protocols.CalDav.Synchronizer.BootstrapCommand.Execute(WorkerStatus status)
09:18:21    at MailClient.Commands.Command.Process(WorkerStatus status)

Is the error only with the CalDAV?

Did you try removing the account, and adding it again?

I receives, but it doesn’t send. I have included a screenshot

OK, that has nothing to do with CalDAV.

Go to Menu > Tools > Accounts and click on the SMTP tab. Make sure that the port is set to  587 and the security policy is set to Force usage of SSL/TLS.

If that still does not work, temporarily disable your anti-virus/firewall application, then try again.

It still doesn’t work. I will try the firewall. 

It usually sends eventually, it just takes a long time. 

I havent been able to send or receive since Sunday. I have tried all of the normal things, modem and router reset, turn pc off and modem reset, ran malware and virus scans etc. Need help. Below is a copy of error messages. It has worked flawlessly until Sunday.
11:33:55 PM    at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
11:33:55 PM    at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
11:33:55 PM    at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
11:33:55 PM    at System.Net.Security.SslStream.AuthenticateAsClient(String targetHost, X509CertificateCollection clientCertificates, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation)
11:33:55 PM    at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
11:33:55 PM    — End of inner exception stack trace —
11:33:55 PM    at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
11:33:55 PM    at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
11:33:55 PM    at MailClient.Commands.Command.Process(WorkerStatus status)
11:33:55 PM jcm34@att.net [POP3]  Connected: To jcm34@att.net
11:33:57 PM jcm34@att.net [POP3]  Downloading messages: From jcm34@att.net
11:33:57 PM jcm34@att.net [POP3]  Disconnected: From jcm34@att.net
11:33:57 PM jcm34@att.net [POP3]  Disconnected: Done