Your email client, plugin or extension said "sent", and it sure did. But your email got stopped just after, and never got sent.
Why? Your SMTP or web host is probably blocking your emails. Quite common. Get in touch with them now to find out.

Make sure you send your emails TO us. We notoriously don't like being CCed or BCCed. We're picky, yes.

We have a known issue with MailChimp, the default "To" field in MailChimp is causing us some problems... To fix this please switch off "Personalize the 'To' field" option on the Campaign setup page.