Error displayed for event registrants with an on-hold bounce email address

Created by: lkuttner

Error below is displayed on the confirmation page when a user with an on-hold bounce address submits an event registration on CiviCRM 5.4.0 using Sparkpost ext 1.3. Registration is recorded and an email does get sent out. Sparkpost error Sparkpost error: HTTP return code 404, Sparkpost error code (Resource could not be found: ). Check https://support.sparkpost.com/customer/en/portal/articles/2140916-extended-error-codes for interpretation.