IP warming
Gradually ramping volume on a new IP to build reputation.
Mailbox providers (Gmail, Outlook, Yahoo) treat brand-new IPs with suspicion. Warming means sending small volumes for the first weeks, ramping up gradually, and prioritizing engaged recipients. Required for dedicated IPs and self-hosted setups.
reading this as early-stage startups
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
Applied to ip warming, that means weighing free tier, best published rate per 1,000, entry price, and developer experience ahead of the rest, against a waitlist, a launch announcement, onboarding email, and the first transactional sends.