The current version of Microsoft Outlook (came out around 2016) has a problem setting up accounts where the login does not equal the email address - which is what we have on the mail.riverland.net.au server. Fortunately the old setup wizard is still hidden in there, and the instructions below will work around the problem.
Click File
Click Account settings. In the list that appears, click the last item, Manage Profiles
Click Email Accounts…
You should now see the usual list with any existing email accounts. Click New..
Select Manual setup or additional server types, and Next
Select POP or IMAP, and Next
On the main Settings screen, enter your name and the new email address. Account type is POP3, mailserver is mail.riverland.net.au (both incoming and outgoing), and your username and password. Tick Remember Password, but not Secure Password Auth.
On the main Settings screen, click More Settings..
Click the Outgoing Server tab. Tick “My outgoing server requires authentication” and “Use same settings as incoming”
Click the Advanced tab. For Incoming, tick “This server requires encrypted (SSL/TLS)” and be sure the port number is 995
Still on the Advanced tab. For Outgoing, for “Use the following type of connection”, select SSL/TLS and be sure the port number is 465
(recommended) on Advanced tab: tick “Leave a copy of messages on the server” and “Remove from server” after 14 days. You can leave them for longer, but this is often enough.
Advanced tab - finally, click OK
Back on the main Settings screen, click Next, and Outlook will check the settings by logging in.
If that succeeds, the setup is complete. If not, read through the error message for clues about what to fix.