Hi again Paul,
Thanks for your reply, and good job about answering my questions on your computing environment. Lots of folks here seem to ignore that request, like I'm a psychic and can figure out what OS & all the hardware goodies they have in front of them.
The first thing that comes to mind is that have you tried the Win10 E-mail sync on a different computer, one such as an OEM built (Dell, HP, Acer, Asus, etc.)? And if so, does it do the same thing? Same error code?
I was fooling around my Sony laptop yesterday, and needed to E-mail something from it, so I tried setting it up with my Verizon webmail using the built-in Win10 Mail app. No go. I tried multiple times. This laptop is about 7 years old, and was upgraded from Vista-Win7 Home-Win10 Home via system tray widget download from Microsoft App store. This laptop is my main entertainment PC and I use it for watching Netflix and take with when I do troubleshooting at my Customer sites. So, it is a very solid machine. Just providing some background for you here, and in case some of the other Mods here are reading this and want to jump in they know what are environments looked like. I have Google and Hotmail (Windows Live ID) accounts, but haven't yet tried those on the laptop yet. I wasn't able to get my Windows Live ID to work on Win10 Mail either (interesting, huh?), and yet it works on my other computers (I have several), and on my main desktop I run Vista with Windows Live Mail 2011, and
BOTH my Verizon webmail works as does my WLM2011 with my Windows Live ID account (Outlook.com). I received no error codes as you did with your Email syncing, it just doesn't work correctly. I get a few E-mails in, but can't send anything. Now on this Sony laptop, prior to my Win10 download/upgrade on July 29th (Win10 release date), WLM 2012 worked just fine with both my Verizon webmail account and my Windows Live ID (Outlook.com) accounts no problem.
My initial conclusion is that Win10 Mail has some kind of syncing errors, some which produce error codes (such as yours, and some that do not, such as mine in the above configuration and situation! More testing will be required. I have another Vista-era PC that I recently installed Win10 Home RTM on manually via DVD ISO file, and will test out the Win10 Mail app on that during the next few weeks and get back to you. It could be server or authentication settings on just my laptop, but I doubt it, as I'm pretty good at E-mail having been an E-mail administrator for several different companies with up to 5,000 computers on their E-mail server. So, if I cannot get the Win10 E-mail app to work with any of my several E-mail accounts, MS probably has a bug in the program. I'll check with some of the other Tech Forums I volunteer on and see what they have to say as well.
So you know also, I've been a Win10 Tech Preview tester for Microsoft (along with 3.9 Million other folks!) since last Sep. 2014 and have been running the preview versions now for a year. I also lead Win10 workshops at my local Computer Club, and have a couple coming up. Right now, the Club's focus is on basic usage, for people who buy brand new Win10 PCs, laptops, or tablets and just want to know how to use them, and on backup including clone image backups (which I have tested extensively).
This really isn't related to your problem, but, I will add the E-mail situation to my list of testing and see what I come up with. My Microsoft buddies on the MS Win10 forums have mentioned a Win10 update that will be released in the next couple of months (for sure by the end of the year) which may or may not address this E-mail problem. We'll have to see.
I've been doing Win10 support on multiple Tech Forums since July 29th, and there are several other problems related to Upgrade & Installation as well. Not entirely unexpected, as we had these types of problems a few years ago when Win8 first came out (2011). For the most part, Win10 does a really good job with the upgrade, but some of the MS app store apps still have some issues. Mostly, since they are new I think as is their distribution method. Some of the folks I work with have had luck with some of the MS Win10 fixit tools. The bottom line is that if your PC is running a pre-Win10 windows version and it is clean, with no viruses or malware, the upgrade whether download version or ISO file install version (DVD or USB) works pretty well!
Your hardware setup appears pretty clean to me, and the only possible issue is the
overclocking. Don't know whether or not your Mobo allows you to temporarily disable the overclock feature or not, but some older ASUS Mobos do allow this;
you might try disabling that feature just long enough to retest your E-mail syncing. It probably won't make a difference, but it could help.
Of course, if you have a 2nd PC that you can use or access (a friend's perhaps) that has Win10 installed on it you can try the E-mail sync on that system (
preferably an OEM build) and see whether you get the same error code on sync or not. If so, let me know, and I'll include that test in my data reports.
Let us know how it goes, and best of luck!
<<<BBJ>>> 
Interesting about the Office365 account issues as well. I don't do much with Office365 as most of my Customers don't like the whole "online subscription" issue and prefer to run the traditional office programs from their hard drives. But it certainly doesn't surprise me. MS has just recently released Office2016, so it would be interesting to get a hold of that (which can be downloaded via ISO file), to see if the Syncing problem remains with Outlook2016. Outlook2016 should be the full-featured local version of Outlook365-Outlook. Haven't tried it as this year my Computer Club has decided that Win10 is more important to our Members than the newest version of Office, so we voted not to do an Office2016 workshop. We'll probably do that next year in the spring. So, I don't intent to devote any resources solving this problem until then.
