That email address cannot be used here
Support/contact returned support.emailBanned (That email address cannot be used here.) when the address is on a block list or disallowed for this form.
Why this happens
Admin email ban/deny list, disposable domains, or prior abuse. Distinct from Enter a valid email address (format) and This email provider is not allowed (registration).
Diagnose and fix
1. Try a different mailbox you control.
2. Members: open a ticket while signed in if contact-by-email is blocked.
3. Admin: review banned emails / provider rules if a legitimate address is blocked.
4. See Contact form (member) / A valid email address is required.