I added a customer myself but they say they never received their login details. Why?

Login details are only emailed if confirmation to send a mail was ticked when you clicked Add User. If it was not, nothing was sent.

To send them now:

1. Go to Customers → Manage Customers and open the customer.
2. On the Change Password tab, enter a New password and Confirm password.
3. Tick Email the new login details to the customer.
4. Click Update & send login details.

If it still does not arrive, check Settings → Web Settings → Email Delivery Logs for the result, and ask the customer to look in spam.