Hi Neil,
I understand that you have encountered an issue that emails cannot be received by recipients via Outlook client and stuck in Draft folder when sending from OWA. Sorry for the inconvenience the issue caused.
I used to see a similar issue which finally turns out to be a server side issue. In order to identify whether you are also in the same situation, I’d like to confirm more information as the following to do a first step narrow-down:
1. Whether there is any other user who also run into the same issue in your organization.
2. Whether there is any other problem when using Office 365 service. For example, clicking the little gear icon on the upper right corner and click Options to access your OWA settings.
3. Check whether you can modify your emails in different folders such as moving, deleting, copying and so on.
At the same time, I have sent a private message requesting the tenant information. Please try the following steps to access the message and provide the information requested in the private message:
• Go to the Your details section on the right side of the community site.
• Click Private messages.
• Click the subject title of the response to read the message.
• You can reply by using the form that displayed.
• Click Submit Reply.