Issue: Outlook 2016 (which I am testing) cannot connect to Office 365 Exchange.
It is no longer possible to manually enter Exchange Server details. A valid Autodiscovery record is required. Use this site to find out which autodiscovery mechanism you are using.
Verifies that we do have a valid autodiscovery record and that we use the HTTP Redirect method. It also shows that Outlook tries several other autodiscovery methods before the correct (for my organisation) HTTP redirect method.
Solution
What is actually happening is that Outlook 2016 on the PC is hanging when performing the HTTPsAutoDiscoverDomain method. We can force it to use the correct method by the following registry entries.
If Outlook is slow finding the autodiscover records, you may need to tell Outlook to exclude the root domain or other records.
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\
DWORD: ExcludeHttpsRootDomain
Value: 1
The other records you can exclude, also under the Autodiscover key are as follows. Use a value of 1 to enable, delete the key if you no longer want to exclude these checks.
DWORD: ExcludeScpLookup
DWORD: ExcludeHttpsAutoDiscoverDomain
DWORD: ExcludeHttpRedirect //I DON’T EXCLUDE THIS ONE BECAUSE I USE IT
DWORD: ExcludeSrvRecord
Dr James Bayley 
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Genius!! HOTMAIL.CA does not work with outlook. Two days of pounding at outlook. MS was no help. This was brilliant. Worked like a charm.
These worked for me too. Not sure what the down side of the fix is but it is all good. Thank you very much
Awesome, looks like you forgot to include ExcludeHttpsRootDomain though
Great job. Credits to you. I found it on another page but wanted to show it to my company
Brilliant! Thank you so much! Worked perfectly.
Ugh, you guys don’t seem to know what you’re talking about or are internet bots posting positive comments. This description and registry change are inconsistent. If you care, you will update this post.
Thanks,
JT
I am sorry that this fix is not working for you. Feel free to post details of your solution.
Thanks – worked!
The best solution after months of battling with this.. Thanks a mil
Tried all above, but non worked out.
Finally figured signing out in any way from Outlook (Go to File, Office Account)
Closed Outlook.
Windows Run: outlook /safe and delete all previous profiles.
Created a new profile with complete different name as before. Started it up and signed in with my 365 emailadres.
Within seconds it was up and running.
Hope this helps to those wwho tried all above without succes.
Thanks for the tip.