how do I insert a horizontal line in an email via New Outlook

how do I insert a horizontal line in an email via New Outlook?

The previous instructions are NOT for the New Outlook.

Its no wonder people keep turning off the toggle button, using previous features, then turning it back on.

Can you just fix this version of outlook already? Its been out long enough that we shouldn't be begging Microsoft for simple features like inserting a horizontal line or using mail merge etc.

These instructions do not work at all. Neither is there a symbol group to insert the line nor can I use "---" or "___" to insert the line.

(Imho it is always a good advice to eat ones own dog food.)

Not sure how long this has been available but I did find a solution to this issue.

When you open a new email, on the far-right side of my screen under Options is the "Auto format options" button. Clicking on that brought up the option to create horizontal lines. The option was unchecked when I opened this. After selecting the option, Outlook started converting underscores and hyphens to horizontal lines.

One workaround is to insert a one-row/one-column table. Make it have no borders and then add back a bottom border. You can change the border color and width so that your horizontal line appears how you wish. Stretch the table to size it appropriately.

This workaround worked for me:
Write your message in Word, use "---" (or any other separator/method), then copy and paste it into the new Outlook.

It's strange, but it worked — so the feature isn't actually missing in the new Outlook; it's just not directly accessible.