# Cold email at scale is an infrastructure problem before it is a copywriting problem

- Category: distribution
- Author: Mihai Negrea (https://indie.md/people/mihai-negrea/)
- Source: https://indie.md/events/indie-tm-12-timisoara-july-2026/
- Canonical URL: https://indie.md/advice/warm-up-a-fleet-of-sending-domains/

Mihai's cold email machine is mostly plumbing: multiple sending addresses spread across several domains, each warmed up automatically by Instantly.ai, which has the accounts send, open, reply to, and click each other's messages until mailbox providers trust them. The whole fleet costs about $150 per month plus $5 per Google Workspace address, and throughput stays deliberately limited to protect deliverability. The insight indie hackers miss is the ordering: before subject lines and personalization matter at all, the message has to land in an inbox, and that is determined by sender reputation built over weeks. Blasting from your main domain both fails and burns the domain your business runs on. Treat cold email like infrastructure, warmed domains you can afford to lose, low volume, patience, and only then start optimizing the words.