Email Warmup

What is Email Warmup?

Email warmup is the process of gradually ramping up volume from a new IP address or sending domain so that mailbox providers learn to trust it. New senders start with zero reputation, and attempting to blast thousands of messages on day one will trigger rate limits, blocks, or placement in spam.

Why it matters

Every new sending infrastructure begins as a stranger to Gmail, Outlook, and Yahoo. If you skip warmup, your first campaign often lands entirely in spam and the damage takes weeks to undo. Founders launching a new product, ops teams migrating ESPs, and marketers spinning up dedicated IPs should plan warmup into the timeline, not bolt it on afterward.

How it works

Warmup follows a schedule that doubles or gently increases volume each day for two to six weeks, starting from a few hundred messages and reaching full production volume at the end. Traffic should be routed to your most engaged recipients first, because opens and replies are the strongest positive signals. Providers track the ramp, and a smooth curve of engaged recipients builds reputation steadily.

Examples

• A startup warming a new dedicated IP from 200 to 50,000 daily sends over 30 days
• A migration team splitting traffic 10 percent to the new IP in week one, then 25, 50, 100
• A marketer seeding the warmup pool with power users who reliably open every message

Best practices

• Warm up the most engaged recipients first, not the coldest
• Follow a published warmup schedule rather than eyeballing it
• Authenticate SPF, DKIM, and DMARC before day one of warmup
• Let Sendkit manage warmup automatically if you are on a shared or dedicated IP

FAQs

How long does warmup take?

Typically two to six weeks, depending on your target volume. Faster ramps are possible but riskier.

Do I need to warm up if I am on a shared IP pool?

A well-maintained shared pool is already warm, so most senders can skip explicit warmup. You should still ramp domain reputation for the sending subdomain.

What happens if I break warmup with a big send?

Expect throttling, deferrals, and a placement dip at the most strict providers. Go back to the last working volume and resume the ramp slowly.