In the notification email the form fields are displayed in a single line without line breaks

Fields values should be placed one per line in the contact email you receive, but Microsoft Outlook has an option (enabled by default) for intentionally ruining plain-text emails by removing carriage returns. Maybe Microsoft doesn't want you to send / receive plain-text emails.

From Microsoft's support website :

By default, the Auto Remove Line Breaks feature in Outlook is enabled. This causes the line breaks to be removed.

How to disable line breaks removal option

1. Open Outlook.
2. On the Tools menu, click Options.
3. On the Preferences tab, click the E-mail Options button.
4. Click to clear the Remove extra line breaks in plain text messages check box.
5. Click OK two times.