An error occurred. object reference not set to an instance of object .

An error occurred. “object reference not set to an instance of object” after updated ver. 7.1.29274

I can’t send e-mail.

check my logs.

오전 7:54:24   System.NullReferenceException: Object reference not set to an instance of an object.
오전 7:54:24    at MailClient.Authentication.Mechanisms.Gssapi.GssapiSession.AcquireCredentials(String packageName, String user, String domain, String password)
오전 7:54:24    at MailClient.Authentication.Mechanisms.GssapiMechanism.Client…ctor(ClientCredential credential, String serviceType, String serverName, String protocolName)
오전 7:54:24    at MailClient.Authentication.Mechanisms.GssapiMechanism.CreateClient(ClientCredential credential, String serviceType, String serverName, TransportContext context)
오전 7:54:24    at MailClient.Protocols.Smtp.SmtpSendCommand.Authenticate(WorkerStatus status)
오전 7:54:24    at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
오전 7:54:24    at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
오전 7:54:24    at MailClient.Commands.Command.Process(WorkerStatus status)