You may receive an exception that resembles the following example when you run the Export-MailboxDiagnosticLogs cmdlet against this mailbox:
Export-MailboxDiagnosticLogs "MailboxAlias" -ComponentName MRM | FL > C:\location\MBXDiag.txt
----------Call Stack from MRM Details--------------------
Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcEwsException: ELC EWS failed with error type: 'ArchiveExchangeWebServiceNotAvailable'. Message: Archive EWS url is unknown.
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.RemoteArchiveProcessorBase..ctor(MailboxSession mailboxSession, ADUser user, StatisticsLogEntry statisticsLogEntry, Boolean isCrossPremise, Boolean isTestMode, MailboxesInformation archiveMailboxesInformation)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ArchiveProcessorFactory.Create(ArchiveLocation archiveLocation, MailboxSession mailboxSession, ADUser adUser, StatisticsLogEntry statisticsLogEntry, Boolean isTestMode, MailboxesInformation archiveMailboxesInformation)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.MailboxData.get_ArchiveProcessor()
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcUserTagInformation.SaveConfigItem(MailboxDataForTags mailboxDataForTags)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.InvokeInternal(MailboxDataForTags mailboxDataForTags)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.Invoke(MailboxDataForTags mailboxDataForTags)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.InvokeInternal(MailboxSession mailboxSession, MailboxDataForTags mailboxDataForTags)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.Invoke(MailboxSession mailboxSession, MailboxDataForTags mailboxDataForTags)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.InvokeCore(MailboxSession mailboxSession, List`1 customDataToLog, StatisticsLogEntry logEntry, ElcParameters parameters)
at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.<>c__DisplayClass30_0.<InvokeInternalAssistant>b__1()
at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2 filterDelegate, Action`1 catchDelegate)