Ошибки синхронизации ящика

Синхронизация вроде проходит, но постоянно горит ошибка, содержимое лога такое:
[Exchange Web Services]Не удалось синхронизировать папку ‘ab@9062606.ru/Отправленные’ из-за ошибки:P’ is not a valid Base64 text sequence.
16:28:22 ab@9062606.ru [Exchange Web Services] MailClient.Storage.Application.OperationException: Не удалось синхронизировать папку ‘ab@9062606.ru/Отправленные’ из-за ошибки: ’ is not a valid Base64 text sequence.
at System.Xml.Base64Decoder.Decode(Char* pChars, Char* pCharsEndPos, Byte* pBytes, Byte* pBytesEndPos, Int32& charsDecoded, Int32& bytesDecoded)
at System.Xml.Base64Decoder.Decode(String str, Int32 startPos, Int32 len)
at System.Xml.ReadContentAsBinaryHelper.ReadContentAsBinary(Byte[] buffer, Int32 index, Int32 count)
at System.Xml.ReadContentAsBinaryHelper.ReadElementContentAsBinary(Byte[] buffer, Int32 index, Int32 count)
at System.Xml.ReadContentAsBinaryHelper.ReadElementContentAsBase64(Byte[] buffer, Int32 index, Int32 count)
at System.Xml.XmlCharCheckingReader.ReadElementContentAsBase64(Byte[] buffer, Int32 index, Int32 count)
at Microsoft.Exchange.WebServices.Data.EwsXmlReader.ReadBase64ElementValue()
at Microsoft.Exchange.WebServices.Data.FileAttachment.TryReadElementFromXml(EwsServiceXmlReader reader)
at Microsoft.Exchange.WebServices.Data.ComplexProperty.InternalLoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName, Func2 readAction) at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName) at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName) at Microsoft.Exchange.WebServices.Data.GetAttachmentResponse.ReadElementsFromXml(EwsServiceXmlReader reader) at Microsoft.Exchange.WebServices.Data.ServiceResponse.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName) at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest1.ParseResponse(EwsServiceXmlReader reader)
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ReadResponse(EwsServiceXmlReader ewsXmlReader)
at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponseXml(Stream responseStream)
at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponse(IEwsHttpWebResponse response)
at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest1.Execute() at MailClient.Protocols.Exchange.ExchangeMailSynchronizer.GetItemContentInternal(Folder folder, IMailRepositoryItem item, IStoredMimePart basePart, String partName) at MailClient.Protocols.Exchange.ExchangeMailSynchronizer.PrefetchItems(IPrefetchProgress progress, Folder folder, IEnumerable1 items, PrefetchType prefetchType, CancellationToken cancellationToken)
at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass38_0.<EnqueuePrefetch>b__2(WorkerStatus status, CancellationToken cancellationToken1) at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status) --- End of inner exception stack trace --- at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status) at MailClient.Commands.Command.Process(WorkerStatus status) EnqueuedStackTrace = at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass38_0.b__0()
at MailClient.Protocols.Common.AccountBase.RunIfOnline(Action actionIfOnline, Action actionIfOffline)
at MailClient.Protocols.Common.ItemSynchronizer2.EnqueuePrefetch(Folder folder, IEnumerable1 items, Int32 countEstimate, Int32 initialProgress, PrefetchType prefetchType, SynchronizationPriority priority, CancellationToken cancellationToken, Action1 completed) at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass37_1.b__6(WorkerStatus status, CancellationToken ct)
at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)
at MailClient.Commands.SynchronizationQueue.ThreadWorker(Object threadData)
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
GUIStatus_Exception_Reported = True