A client of mine recently reported a problem sending mail via Outlook 2013. The error in question was 0x800CCC13 – the Outlook test send and receive worked but no mail was being sent. We checked all of the SMTP settings, tried various ports and mail hosts but nothing was fixing it. My client then told me that he had recently updated to Windows 10 and the problems started around that time. It seems that the update was responsible, but thankfully there is an easy fix.
You need to have Administrator access and be able to run an elevated command prompt (you can do this by right clicking on it and running it as Administrator) – then, simply type in the following:
This solved the problem for my client – hopefully it will save someone else from having to do so much investigation!