Enable Messaging in Moodle advanced features Enable "Allow site-wide messaging" in the same page Create or use three existing users: u1, u2 and u3 Log-in as u1, go to your Preferences -> Notification preferences and check that for the "Message contact requests notification" field the column Web is set to On / On Log-in as a u2, go to the "Messages" icon (top right), search for u1 and click on their profile.  Send to u1 a contact request via [...] menu -> Add to contacts -> Add Log-in as u1 and check there's a new notification in notification bell icon. Click on 'u2 wants to be added as a contact' link.  Check you have both 'Accept and add to contacts' and 'Decline' options. Click on 'Accept and add to contacts' and check once the page has been reloaded you can see u2 - Accepted. Go to the "Messages" icon (top right) -> Contacts and check u2 is listed as a contact. Log-in as a u3, go to the "Messages" icon (top right), search for u1 and click on them profile.  Send to u1 a contact request via [...] menu -> Add to contacts -> Add Log-in as u1 and check there's a new notification in notification bell icon. Click on 'u3 wants to be added as a contact' link.  Click on 'Decline'. Go to the "Messages" icon (top right) -> Contacts and checked u3 is not listed as a contact.