Event ID 4009

Question

Anybody ever see this error before? I see it intermittently and it just started a few weeks ago, even though we have been on exchange 2013 for a few months now. No issues have been reported by users (no tickets or calls complaining of connection
issues) Any help would be appreciated!
Description: Process Microsoft.Exchange.InfoWorker.Common.Delayed`1[System.String]: Unable to open connection for mailbox <user>SMTP:[email protected]. Exception returned is: Microsoft.Exchange.Data.Storage.StorageTransientException: Cannot open mailbox
/o=xxxxx/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EXCH2013/cn=Microsoft System Attendant. ---> Microsoft.Mapi.MapiExceptionRpcServerTooBusy: MapiExceptionRpcServerTooBusy: Unable to make connection to the server.
(hr=0x80004005, ec=2419) Diagnostic context:
Lid: 41841   StoreEc: 0x973    
    Lid: 51059 
    Lid: 62321   StoreEc: 0x973    
    Lid: 47987 
    Lid: 50033   StoreEc: 0x973    
    Lid: 50544   ClientVersion: 15.0.847.32
    Lid: 52080   StoreEc: 0x973    
    Lid: 51152 
    Lid: 52465   StoreEc: 0x973    
    Lid: 60065 
    Lid: 33777   StoreEc: 0x973    
    Lid: 59805 
    Lid: 52487   StoreEc: 0x973    
    Lid: 19778 
    Lid: 27970   StoreEc: 0x973    
    Lid: 17730 
    Lid: 25922   StoreEc: 0x973    
   at Microsoft.Mapi.MapiExceptionHelper.InternalThrowIfErrorOrWarning(String message, Int32 hresult, Boolean allowWarnings, Int32 ec, DiagnosticContext diagCtx, Exception innerException)
   at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, IExInterface iUnknown, Exception innerException)
   at Microsoft.Mapi.ExRpcConnectionFactory.Create(ExRpcConnectionInfo connectionInfo)
   at Microsoft.Mapi.MapiStore.OpenMapiStore(String serverDn, String userDn, String mailboxDn, Guid guidMailbox, Guid guidMdb, String userName, String domainName, String password, String httpProxyServerName, ConnectFlag connectFlags,
OpenStoreFlag storeFlags, CultureInfo cultureInfo, Boolean wantRedirect, String& correctServerDN, ClientIdentityInfo clientIdentity, Boolean unifiedLogon, String applicationId, Client xropClient, Boolean wantWebServices, Byte[] clientSessionInfo, TimeSpan
connectionTimeout, TimeSpan callTimeout, Byte[] tenantHint)
   at Microsoft.Mapi.MapiStore.OpenMailbox(String serverDn, String userDn, Guid guidMailbox, Guid guidMdb, String userName, String domainName, String password, ConnectFlag connectFlags, OpenStoreFlag storeFlags, CultureInfo cultureInfo,
WindowsIdentity windowsIdentity, String applicationId, Byte[] tenantPartitionHint, Boolean unifiedLogon)
   at Microsoft.Exchange.Data.Storage.MailboxSession.ForceOpen(MapiStore linkedStore, Boolean unifiedSession)
   --- End of inner exception stack trace ---
   at Microsoft.Exchange.Data.Storage.MailboxSession.ForceOpen(MapiStore linkedStore, Boolean unifiedSession)
   at Microsoft.Exchange.Data.Storage.MailboxSession.Initialize(MapiStore linkedStore, LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags, GenericIdentity auxiliaryIdentity,
Boolean unifiedSession)
   at Microsoft.Exchange.Data.Storage.MailboxSession.<>c__DisplayClass1a.<CreateMailboxSession>b__18(MailboxSession mailboxSession)
   at Microsoft.Exchange.Data.Storage.MailboxSession.InternalCreateMailboxSession(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegatedUser, CultureInfo cultureInfo, String clientInfoString, IBudget budget, Action`1
initializeMailboxSession, InitializeMailboxSessionFailure initializeMailboxSessionFailure, MailboxSessionSharableDataManager sharedDataManager)
   at Microsoft.Exchange.Data.Storage.MailboxSession.CreateMailboxSession(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags, CultureInfo cultureInfo, String
clientInfoString, PropertyDefinition[] mailboxProperties, IList`1 foldersToInit, GenericIdentity auxiliaryIdentity, IBudget budget, Boolean unifiedSession, MailboxSessionShar

Answer 1

Hi,
Based on the error message, MapiExceptionRpcServerTooBusy, it seems that this issue is related to the client throttling policy.
I recommend you check the throttling policy for this user, if possible, you can create a new throttling policy for this user to check the result.
Here is a related article for your reference.
Understanding Client Throttling Policies
http://technet.microsoft.com/en-gb/library/dd297964(v=exchg.141).aspx
Best regards,
Belinda
Belinda Ma
TechNet Community Support