not able to register Vendor

Everything was working fine, until a week back. Not sure what the reason was. Now the Vendor Registration doesn’t seem to be working on our Website.
On signup as a vendor, they get a confirmation message on screen, but no mail is sent to the admin and their registration doesn’t show up on the Pending Approval page either for the admin. They end up as subscribers.
Since it doesn’t show up on the pending approval page or on the notifications, there is no way to approve these Vendor Applications.
Please help it’s urgent.

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