Symptoms
When issuing a Let's Encrypt certificate, the operation fails with the error message:
Could not issue a Let's Encrypt SSL/TLS certificate for domain.tld.
...
You might have specified an invalid email address.
Please specify a valid email address and request the SSL/TLS certificate again.
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Detail: Error creating new account :: contact email "[email protected]" has invalid domain : Domain name does not end with a valid public suffix (TLD)
Cause
An invalid email address has been used for issuing a Let's Encrypt certificate.
Resolution
Use a valid email address when issuing a Let's Encrypt certificate.