Outlook Mobile / Apple Mobile Mail & Shared Mailboxes

I recently got escalated an issue around a shared mailbox failing to send from a mobile client only. From OWA and Outlook it was fine. Bring an activesync device into the mix and it just failed.

In the end, and the full errors are below, it turned out to be that the “Linked Master Account” was still set – likely inherited from 10 years ago when we ran Exchange 2007, then Exchange 2010, then Exchange 2013 and then when we saw this, Exchange 2019.

To confirm it:
Get-Mailbox <yourmailbox> | Select LinkedMasterAccount
It will likely return NT AUTHORITY\SELF
We want it to be Null / Blank

To fix it:
Get-Mailbox <yourmailbox> | Set-User -LinkedMasterAccount $Null
You will need to wait upwards of 20 minutes for it to take effect AND restart the devices that were using it from my testing

Props to these URLs for helping
TechNet Post 1
TechNet Post 2
Dump ActiveSync Logs

Happy log fun time!

In outlook mobile we saw:

EasSendFailedPermanentException: An EAS Send command failed: The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK. --> The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK. Failure code: 38db

Or

EasSendFailedPermanentException: An EAS Send command failed: The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK. --> The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK. Failure code: 547

In Apple we saw: 
 "Failed to Send message" - yep , thanks Apple. 

If you dump the ActiveSync Device logs, which i would recommend, you might see this against the SendMail command:

Exception stack trace: at Microsoft.Exchange.AirSync.Common.SendMailBase.SendMessage(MessageItem sendMessage)
at Microsoft.Exchange.AirSync.SendMailCommand.ExecuteCommand()
at Microsoft.Exchange.AirSync.Common.Command.WorkerThread()
Inner exception follows…
Exception type: Microsoft.Exchange.Data.Storage.SendAsDeniedException
Exception message: Cannot submit message.
Exception level: 1
Exception stack trace: at Microsoft.Exchange.Data.Storage.MapiAccessor.SubmitMessageEx(MapiMessage mapiMessage, SubmitMessageExFlags submitFlags)
at Microsoft.Exchange.Data.Storage.CoreItem.<>c__DisplayClass76_0.b__0()
at Microsoft.Exchange.Data.Storage.MessageItem.InternalSend(StoreObjectId saveSentMessageFolder, SubmitMessageFlags submitFlags, Boolean doNotMove, Boolean shouldSkipPDLMembersWithoutSMTP)
at Microsoft.Exchange.Data.Storage.MessageItem.Send(SubmitMessageFlags submitFlags)
at Microsoft.Exchange.AirSync.Common.SendMailBase.SendMessage(MessageItem sendMessage)
Inner exception follows…
Exception type: Microsoft.Mapi.MapiExceptionSendAsDenied
Exception message: MapiExceptionSendAsDenied: Unable to submit message. (hr=0x80070005, ec=1244)