Hi everyone
I have a suggestion for something that appears to be helping manage this. If, once you've pressed send on an email, you don't do anything more in outlook until the email is sent, the email seems to actually send. This appears to work pretty much all the time that I've tried it over a month. It seems bizarre that this would have any impact, but I can only assume that activity in Outlook could be interfering with the send process.
I'd be grateful for those who'd be willing to verify that the same happens for them. We live in hope of solution, but this work around seems to offer me some relief.