I am a desktop support tech for my company. We have a user who has had this ongoing issue with her shared mailbox. This was happening on Outlook 2016, and now O2019 as well (fresh image/profile). Some of the emails she sends will get stuck in the outbox, while others seem to make it just fine.
When emails were getting stuck again in our new image with O2019, I tried to take that mailbox off cached mode, and I deleted the ost. I was hoping that would fix this, but there are a couple emails stuck in the outbox again. When these emails stuck in the outbox, there is also an error that states:
There is no data file on the PC for the shared mailbox that is giving us this error, since I turned cached mode off. I don't have access to the exchange server, but can send this issue to out exchange admin if there is nothing I can do on the client at this point. So, that is my question: Is there anything I should be trying on the local outlook client? I've searched for answers, but the only one I seem to be able to find is recreate the profile, which has been done a number of times at this point.