I work for one company that has their own email host and am using an Exchange account there. I also own and manage a domain hosted in O365 (related business) and have both set up within the same desktop Outlook. Shared mailboxes on the external host are actually set up as users with full permissions granted to applicable people (their structure, not my choice) and work good with sending as the mailbox.
The issue is that I have also created Shared Mailboxes in the O365 hosted and it appeared just fine (automatically) and can receive and view email just fine, but whenever I try to send an email as the shared mailbox it gives the below returned email:
This message could not be sent. You do not have the permission to send the message on behalf of the specified user.
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Diagnostic information for administrators:
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Error is [0x80070005-0x000004dc-0x00000524].
Exchange response headers:
request-id: aae735ff-61a0-4303-8308-9b92431ba2c9
X-ServerApplication: Exchange/15.01.2308.020
X-FEServer: PRDH02EXCH06
X-BEServer: AUSH02EXCH05
X-CalculatedBETarget: aush02exch05.h02.hostedmail.local
X-RequestId: {239F18EC-9F78-4274-B8BB-AACBBF2D6480}:34
X-ClientInfo: {FE2C7307-DA5C-4819-8A5A-AB654815073B}:19440066
X-ElapsedTime: 40
X-ResponseCode: 0
X-DiagInfo: AUSH02EXCH05
X-RequestType: Execute
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ROPs Summary:
0: ropSetProps (10) Processed(1) Completed(0)
ROP result: 0
Response codes: 0
1: ropSetProps (10) Processed(1) Completed(0)
ROP result: 0
Response codes: 0
2: ropFlushRecipients (14) Processed(1) Completed(0)
ROP result: 0
Response codes: 0
3: ropSetProps (10) Processed(1) Completed(0)
ROP result: 0
Response codes: 0
4: ropTransportSend (74) Processed(1) Completed(0)
ROP result: 0
Response codes: 1244
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Response Exceptions:
ROP Index: 4
ROP Associated: ropTransportSend (74)
Microsoft.Exchange.Data.Storage.SendAsDeniedException: Can't transport send message. ---> Microsoft.Mapi.MapiExceptionSendAsDenied: MapiExceptionSendAsDenied: Unable to transport send message. (hr=0x80070005, ec=1244)
Diagnostic context:
......
Lid: 52176 ClientVersion: 15.1.2308.20
Lid: 50032 ServerVersion: 15.1.2308.6020
Lid: 35180
Lid: 23226 --- ROP Parse Start ---
Lid: 27962 ROP: ropFlushRecipients [14]
Lid: 27962 ROP: ropFlushRecipients [14]
Lid: 31418 --- ROP Parse Done ---
Lid: 55847 EMSMDBPOOL.EcPoolSessionDoRpc called [length=166]
Lid: 43559 EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=456][latency=3]
Lid: 52176 ClientVersion: 15.1.2308.20
Lid: 50032 ServerVersion: 15.1.2308.6020
Lid: 35180
Lid: 23226 --- ROP Parse Start ---
Lid: 27962 ROP: ropSetProps [10]
Lid: 27962 ROP: ropTransportSend [74]
Lid: 17082 ROP Error: 0x4DC
Lid: 44949
Lid: 21921 StoreEc: 0x4DC
Lid: 27962 ROP: ropExtendedError [250]
Lid: 1494 ---- Remote Context Beg ----
Lid: 1238 Remote Context Overflow
Lid: 57132 qdwParam: 0x0
Lid: 36423 dwParam: 0x0 Msg: /o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=e2b94478e7da4981b8c
Lid: 42092 StoreEc: 0x4DC
Lid: 33900
Lid: 45434 Guid: 59a65903-75b3-491a-bb25-4b628107efde
Lid: 10786 dwParam: 0x0 Msg: 15.01.2308.020:aush02exch05:0c665abf-774e-4624-a7a2-5e643ce17afc
Lid: 1750 ---- Remote Context End ----
Lid: 31418 --- ROP Parse Done ---
Lid: 22753
Lid: 21817 ROP Failure: 0x4DC
Lid: 59285
Lid: 46997 StoreEc: 0x4DC
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.MapiMessage.TransportSendMessage(PropValue[]& propsToReturn)
at Microsoft.Exchange.Data.Storage.MapiAccessor.TransportSendMessage(MapiMessage mapiMessage, PropValue[]& mapiPropValues)
--- End of inner exception stack trace ---
at Microsoft.Exchange.Data.Storage.MapiAccessor.TransportSendMessage(MapiMessage mapiMessage, PropValue[]& mapiPropValues)
at Microsoft.Exchange.Data.Storage.CoreItem.TransportSend(PropertyDefinition[]& propertyDefinitions, Object[]& propertyValues)
at Microsoft.Exchange.RpcClientAccess.Handler.Message.TransportSend()
at Microsoft.Exchange.RpcClientAccess.Handler.RopHandler.<>c__DisplayClass153_0.<TransportSend>b__0()
at Microsoft.Exchange.RpcClientAccess.Handler.ExceptionTranslator.TryExecuteCatchAndTranslateExceptions[TResult](Func`1 protectedCode, Func`2 errorCodeExtractor, Boolean noThrow, TResult& result, Exception& exception, ErrorCode& errorCode)
Transport-Send failed: failure enum(25), HResult(0x00000000), EC(1244).
Transport-Send failed: failure enum(22), HResult(0x00000000), EC(1244).
Submit-Message failed: message id(1), failure enum(13), HResult(0x80070005), EC(1244).
