Many thanks Crazycat.
I had not enabled the logs - I shall give this a go now and report back any errors it captures.
Many thanks.
Issue resolved (human error) - I had set a completely different E-Mail address in the 'Admin Email' field than what was being used within the SMTP Settings.
Office 365 will not allow you to send from any other E-Mail Address to prevent spoofing.
Many thanks for all your appreciated help and assistance Crazycat.
I had not enabled the logs - I shall give this a go now and report back any errors it captures.
Many thanks.
Issue resolved (human error) - I had set a completely different E-Mail address in the 'Admin Email' field than what was being used within the SMTP Settings.
Office 365 will not allow you to send from any other E-Mail Address to prevent spoofing.
Many thanks for all your appreciated help and assistance Crazycat.