What happens when you mark an email as unread?

[seo.gops]

What happens when you mark an email as unread?

[anjali raghav]

If you want to remember to read a message later, you can mark it as unread. You can also mark messages as read without opening them.

[Alina Fernandiz]

When you mark a message as unread, it will simply come up above in the list with all other unread messages.