posthaste-rails

https://github.com/posthastemail/posthaste-rails

Send Rails mail through Posthaste by setting one delivery method. Every mail() call, view, deliver_later and mailer test stays exactly as it is. Maps the whole Mail::Message — HTML and text parts, Cc, Bcc, Reply-To, attachments and custom headers — and turns each API refusal into its own exception, so a suppressed recipient, an unverified domain and an exhausted quota are three different things to rescue.