Nobody wants their emails landing in spam.

Warming up your inbox is how you avoid it. Email warmup has a reputation for being slow and tedious, which puts people off before they start.

So how long does it actually take, and how much work is it? Here's the real answer.

Email warmup means slowly increasing your sending volume and frequency to build a sender reputation.

Start a new sending domain, or revive one with a bad reputation, and you can't send at full volume on day one. You begin with a handful of emails and increase the count each week.

Volume is only half of it. Engagement is the part people forget. Your warmup emails need opens and replies, because that engagement tells inbox providers your email is wanted, not spam. Rising volume plus real engagement is what earns you a stable sender reputation.

Here's a step people skip. When you buy a fresh domain, don't send anything from it for the first four weeks. Let it sit. New domains draw scrutiny, and giving it a month to settle clears that initial suspicion before you ever start warmup.

Same logic on a brand new mailbox. Don't start fresh conversations in week one. lemwarm has an answer-only mode that replies to warmup emails in the pool without kicking off new threads, which is exactly what a new inbox should be doing at first.

Plan for about a month, in four phases.

2. Stabilization: hold at 40 a day for another 1 to 3 weeks until your lemwarm score sits above 90.

3. Volume switching: lower your lemwarm volume and start sending real campaigns in lemlist. Your total daily volume never jumps past 40 per mailbox, it just shifts from warmup to outreach. (For now this switch is manual. Automatic switching is coming later this year.)

4. The reputation checker: keep about 10 warmup emails running in the background at all times. Warmup emails carry no links, no images, and no sensitive content, so they're the cleanest mail you send and the most likely to reach the inbox. That makes them a perfect canary. If spam placement spikes in warmup while you're running campaigns, your outreach is dragging your reputation down and you should pull back.

The current setup guidance is to wait until your score is above 90 and you've held 40 a day for a week or two before you rely on the inbox for outreach. Time and score, both. Don't launch on the calendar alone.

Most people use a warmup service rather than doing it by hand, because doing it by hand is a lot of work. Once it's set up, the service runs on its own. Connect your inbox, turn warmup on, and go build your campaigns.

One common mistake: switching warmup off once the initial ramp is done. Honestly, this is the step most people skip, and it's the one that quietly saves their reputation. Keep it running at 10 to 20 emails a day even after campaigns start, so the warmup traffic balances out the lower engagement your outreach gets.

A few things move the timeline:

If a mailbox drops below a health score of 80, don't kill it right away. Put it in answer-only mode for a week with no daily limit, let it just reply inside the warmup pool, then give it two weeks total before you ramp again. If the score recovers within about four weeks, the mailbox is safe. If it doesn't, the reputation is broken and you're better off retiring it and warming a fresh one.

Almost none, if you use a tool like lemwarm.

By hand, warmup is a slog: you're sending dozens of emails a day, chasing replies, and you can never stop. With lemwarm it's three steps:

A decent warmup tool shows you where your emails land, so you can tell if your strategy is working.

In lemwarm, you watch the lemwarm score, your inbox versus spam ratio, and the volume you're sending. The score breaks down into two parts: 70% comes from fixed factors like domain age and your SPF, DKIM, and MX setup, and 30% comes from your inbox rate over the last two weeks. Aim for a score above 90 with a spam rate of 1 to 2% before you launch.

If too many warmup emails land in spam, it's time to change something. lemwarm also flags deliverability issues as they surface, so you catch small problems before they turn into big ones.