Mailin

Mailin is a pure infrastructure play in the deliverability category — if your SDR team, agency, or founder-led outbound is bleeding into spam folders because you're on shared IP pools, this is the category of fix you need. The REST API is available and capable enough that you can wrap Mailin into your own automation layer or MCP orchestration stack without much friction — provisioning new client domains programmatically is a real use case here. At budget tier 3, starting at $299/month for 200 mailboxes, you're paying for an experienced operator to get value out of it — vanilla setup without a deliberate domain warming and rotation strategy will leave the deliverability guarantee untested. The honest gap is that Mailin stops at infrastructure: there's no sequencing, no reply tracking, and no campaign analytics, so you're committing to a two-tool stack minimum before you send a single email.