ruby - Failover solution for Email Service Providers (ESPs)? -

we looking library, project, or service lets transparently use multiple email service providers ("esps", e.g. constantcontact, jangomail, sailthru, sendgrid, verticalresponse, etc). esp choose have problems time time, , because of requirements of our business need have failover solution in place avoid delivery failures.

basic features we're looking for:

• delegation of email delivery esps
• automatic failover 1 esp (only delivering one email given subscriber, not duplicates)
• ability check delivery status (open rates, bounce rates, list size, etc.) across configured esps

in other words, want layer provides failure tolerance , recovery using multiple esps. if library, written in ruby (but might open considering other languages). is there existing project or service provides this?

our use case: send many time-sensitive emails day subscribers. however, esp use can go down, still need send emails in timely manner (within seconds of publication). if initial delivery fails, move secondary, tertiary, etc. esp recover failure.

i've come empty handed when searching existing solution. these 2 blog posts capture part of our motivation, though: how ensure email gets delivered, using multiple service providers mitigate risk , avoid failure

we ended writing our own service this.