As of early December, as per a partly relevant message a few days ago, you can’t use Custom Domains from Office Outlook and Windows Mail apps. You have to migrate to Office 365.

I have a Custom Domain for my web site: http://www.Sportronics.com.au

A Custom Domain where you register your own domains, Sportronics.com.au in my case, and Windows, Outlook.com,  live.com, or Hotmail let you create accounts using that domain rather than XXX@outlook.com eg.; me@mydomain.com.au . That way you do not need to run a mail server to service your domain. You  were allowed, I think, 5 such accounts.

Earlier this year Microsoft announced that they were truncating the capability in that you could not add new domains but said you could continue to use existing Domains as previous… At least that is what I understood. As of early December I found that I could not sync the Outlook and Mail apps with outlook.com for a custom Domain account. I could login Outlook.com with my Custom Domain account via the web interface, as the only way to get to these emails.  This was slow an cumbersome.. My live.com.au account continues to work OK. Note form Microsoft:

Please note that after evaluating our custom domain service in Outlook.com we have made the decision to no longer support new custom domain sign ups and encourage those in need of domain services to use Office 365. For many custom domain administrators, Office 365 is an ideal service, providing access to its many productivity tools including shared calendars, cloud storage, …..

For more information about Office 365 for business, please visit this link. 

Microsoft ends support for custom domains in free email service  .. A discussion of this on ZDNet.

I posted a query wrt this issue but got now answers:

https://answers.microsoft.com/en-us/outlook_com/forum/oemail-oapps/cant-sync-outlook-app-account-2016-post-nov-1-2016/f7f9afac-bfca-4015-95a3-ee9befddcb99?tm=1482260906197

A message was sent late last week indicating that for Custom Domains (with Office 365) you need to re-add your account to the Outlook app.

Reconnect Outlook 2016 or Outlook 2013 to Outlook.com for uninterrupted email access

So I took this to mean that my Custom Domain email address in Outlook.com was dead unless I wanted to login to Outlook.com via the web interface .. a pain.

I have a single user Developer Office 365 account so I decided to recreate the me@mydomain.com.au  account there. I needed to keep this account active as I use it for many things. With some trial an error and much dancing with my Domain name registry settings, I eventually got it all to work.

I created an account me@mydomain.inmicrooft.com which had the Developer’s license assigned when I first setup Office 365

I added my mydomain.com.au domain to the account.

There is a discussion of this at : Create DNS records for Office 365 at any DNS hosting provider

This took a bit of trial and error but there is a check within the domain setup of DNS settings.

As a first try I tried to alias me@mydomain.inmicrooft.com to my me@mydomain.com.au but this failed.

I then added my me@mydomain.com.au account

I detached the Developer license from the onmicrosoft account  and gave it to my me@mydomain.com.au account. No email otherwise.

Eventually I was again able to send and receive emails using me@mydomain.com.au  in the Outlook and Windows Mail apps.

Footnote

When you get your account going in Office 365 you need to get your “old” mail data into your new account.

Overview of importing PST files and SharePoint data to Office 365 covers this. I found a simpler way. Just back up your folders on the Outlook app for the account into a .PST file. When the new account is set up in the app, connect the .PST file tin the app and drag an drop the data in the  file in the new account in the Outlook app. At least something was easy; except I didn’t backup all of my data!

PS

• After these changes MSDN said I had no subscription. But this was available next day.
• Now the Azure Portal says I have no subscriptions!! Waiting on a response to a query on this. Hopefully its a similar problem to MSDN .. ie Time will heal it.
  See comment below for the resolution of this issue.