Mailin – Receive inbound emails in your web app with Node.js
mailin.io
mailin.io
Reading through the source it looks like it spawns a child_process per-message to for checking both SPF and DKIM via a python script... That feels inefficient, but I don't know if there's a better node-based solution.
I once managed a commercial mail filtering company on the perl-predecessor, qpsmtpd, which I documented here: