So at this point I dont think it is the machine its-self as it has been completely reformatted with a new OS?.
We replaced the hard drive in that machine and installed a fresh copy of Win 10, and a new licensed copy of office 2016 pro plus thinking that Win 8 may be the culprit. Initially the problem was occuring on Win 8.1 Office 2016. etc etc, but they are only temporary fixes and the problem returns anywhere within a few minuites to several days.
reformatting the laptop with windows 10,.The issue is limited to this particular laptop and account only. The same email account is also being used on other laptops a mac and an iphone which are NOT experiancing this issue. The machine has to be restarted and then they send immediatly upon opening outlook. Some emails send up until a point and then it randomly stops. This particular account has intermittent issues with sending and emails just sit in the outbox. We have 10-15 office 365 exchange email accounts and they all work perfectly fine apart from one account on one device.
Ok this is a weird one and its been ongoing for many months, wondering if anyone has any ideas.