Email Warmup Calculator

Send 50,000 emails from a brand-new domain on day one and you'll land in spam everywhere. ISPs have never seen your domain before, have no reputation data, and will treat you like a spammer until you prove otherwise. Email warmup is the process of sending gradually increasing volumes over weeks, letting ISPs build a positive reputation profile for your domain and IPs. This calculator generates a day-by-day schedule based on your target volume, so you know exactly how many emails to send each day.

Why warmup is non-negotiable

Gmail, Microsoft, and Yahoo all track sender reputation at both the domain and IP level. When they see a new sender, they start with low trust and adjust based on engagement signals — opens, clicks, replies, and spam complaints. If your first emails get good engagement (because you're sending to your most active subscribers), the ISP raises your trust score and allows more volume. If they get ignored or marked as spam, your reputation tanks before it even starts. There's no shortcut around this process.

How a warmup schedule works

A typical warmup starts at 20-50 emails per day and roughly doubles every 2-3 days. By week 2, you're at a few hundred per day. By week 4, a few thousand. By week 6-8, you should be at your target volume. The exact ramp depends on your goal — warming up to 10,000/day takes about 4 weeks, while 100,000/day takes 6-8 weeks. During this time, send only to your most engaged subscribers — people who've opened or clicked in the last 30 days. Their positive engagement is what builds your reputation.

What to do before you start warming up

Authentication must be locked down before you send a single email. Set up SPF, DKIM, and DMARC for your sending domain. Verify your records with our DNS propagation checker. Set up a proper List-Unsubscribe header so recipients can opt out cleanly (required by Gmail and Yahoo). Check your domain age with a WHOIS lookup — ideally, your domain should be at least 30 days old before you start warming. And run your content through a spam word checker to avoid trigger words during this critical period.

Monitoring during warmup

Track these metrics daily: delivery rate (should stay above 95%), bounce rate (should stay below 2%), spam complaint rate (must stay under 0.1%), and open rate (should be consistently high since you're sending to engaged users). If any of these deteriorate, slow down — reduce volume by 50% and hold for a few days before resuming the ramp. Run weekly blacklist checks on your sending IPs. Use campaign analytics to track trends over the warmup period.