Unable to issue/renew a Let's Encrypt certificate in Plesk: Error creating new account :: "" is not a valid e-mail address

Symptoms

• A Let's Encrypt certificate cannot be issued for a domain.

• The following error message appear in /usr/local/psa/admin/logs/panel.log:

  CONFIG_TEXT: ERR [extension/sslit] Failed to renew certificate of domain 'example.com': Invalid response from https://acme-v02.api.letsencrypt.org/acme/new-acct.
  Details:
  Type: urn:ietf:params:acme:error:invalidEmail
  Status: 400
  Detail: Error creating new account :: "" is not a valid e-mail address

  ---

  CONFIG_TEXT: ERR [extension/sslit] Failed to renew certificate of domain 'example.com': Invalid response from https://acme-v02.api.letsencrypt.org/acme/new-acct.
  Details:
  Type: urn:ietf:params:acme:error:invalidEmail
  Status: 400
  Detail: Error creating new account :: "" Domain name does not end with a valid public suffix (TLD)

• No email address is specified in Let's Encrypt for this domain:

  # plesk db "select d.name, dp.val from domains d join dom_param dp on dp.dom_id = d.id where param='ext-letsencrypt-registrationEmail' and d.name='example.com';"
  +-------------+-----+
  | name        | val |
  +-------------+-----+
  | example.com |     |
  +-------------+-----+

Cause

The email address of the subscription owner is not set at Domains > example.com > Subscription Info (in the right pane) > Subscriber: John Doe > Edit Contact Info (in the right pane):

Resolution

1. Log in to Plesk.

2. Go to Customers > John Doe > Edit Contact Info (in the right pane) and set an email address for this customer.

   Note: The email address used for Let's Encrypt certificate notifications can be set to another one when issuing a Let's Encrypt certificate.