Accounts... in the top menu
Add Email Account. If you do not see this choice, click on the plus icon in the lower left.
Enter your email address and click on
When the screen below appears, choose
Not IMAP/Not Exchange
IMAP/POP to make the advanced settings appear.
Enter the account information like in the screenshot below, and then click on
mittnavn1 with your email account's username.
Please note that the username and email address are not the same thing: How do I manage email accounts?
If everything went correctly, the below image will appear:
Done, and the email client is ready for use!