Problem with email link

Hi, when a message is sent to another user they get an email that looks like this for example:

You have received a new message in

Warframe Data

From: xxxxx

Subject: RE: Riven Market – The Marketplace for Rivens Please Click the following link to view full Message.

/wp-admin/admin-ajax.php?fepaction=messagebox

What I don’t like about this is the link that is not working, how can i fix this?

the link should appear as something like this warframedata.com/riven-market/

The page I need help with: [log in to see the link]