Trying to Email Registrants from the tab under Manage Registrations. I get this error: Unable to send e-mail. Contact the site administrator if the problem persists. for every email address that does not have the same domain as the site. The email that has the same domain delivers fine. Other modules are able to email to other domains just fine: Simplenews, Private Message. Mail System 7.x-2.34, Mime Mail 7.x-1.0-beta3
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.