Shared folder recipient's email appears in yellow and invite is not sent

[Alan B.16]

I enter a recipient's email address and it is yellowed out as if to indicate that it not good. When I hit send, the system shows sending, but the recipient does not show up as a member of the folder, nor do they receive the link

[Hannah]

Hi there, @Alan B.16, thanks for reaching out to us.

Do you currently have an individual or a team Dropbox account?

What about your recipient? Do they have an individual account?

And if they take a look at their "shared" page, do they perhaps see the folder there?

Let me know and we'll go from there.